25 Sep, 2022

How to Identify the Amaranthaceae Family

Introduction to the Amaranthaceae Family

The Amaranthaceae family is part of the Caryophyllales order of core eudicots (dicots). When you learn to identify the Amaranthaceae family, you will see it is made of mostly herbs or shrubs. Many are often found growing in disturbed habitats, and many of them are introduced weeds, sometimes considered noxious. However, many edible plants come from the Amaranthaceae, including commercially important ones. Apart from being weedy, the family is known for having flowers that are very small and often hidden by more conspicuous bracts.

Most of us will recognize this family as weeds, often noxious ones, like certain Amaranth, Salsola, Iresine, and Bassia, to name a few. They are hardy herbs or sub-shrubs that can grow in deserts, saline or alkaline soils, and extreme heat. I have always thought that instead of waging war on amaranth with glyphosate (to which most are now resistant, which is why we have “Roundup Ready” crops so they can still kill the amaranth without killing the crops), we should grow it and eat it instead. It will grow in marginal lands already badly degraded by conventional farming (chemicals and tilling), and it needs very little water and very little fertilizer. You can also harvest about 60-80% of the leaves (eat them like spinach; they are delicious) without it impacting seed production. Seeds can be eaten in porridge or ground into a gluten-free flour for baking with (mmm… zucchini bread and carrot cake). It is far more nutritious than the corn and wheat fields it competes with. Lesson: We should eat our weeds instead of poisoning ourselves while trying to kill them!

Common Botanical Description

If you’re new to plant morphology, this guide is a perfect beginner’s description to teach you how to identify the Amaranthaceae family, with no need to know any scientific jargon. Below is additional information on uses and morphology, as well as pictures to help identify family members and individual species found in North America. But for researchers or those wanting to learn a more in-depth version, check out the Scientific Botanical Description below the images in addition to genus-level distribution data.

Leaves and Stems of the Amaranthaceae: Most members are annual or perennial herbs or shrubs, sometimes described as sub-shrubs due to their somewhat woody nature. Stems often have thickened joints (nodes) and may become fleshy (succulent) in some species (especially Chenopodioideae). Leaves vary in size from tiny scales to large, well-developed leaves but are also occasionally absent. Leaves are usually simple (not compound) and may be in opposite pairs or alternately arranged along the stem.

Flowers of the Amaranthaceae: Flowers are usually very small to minute and grow in spikes, heads, tight clusters, or branched groups. They are most often accompanied by conspicuous papery leaf-like structures (bracts) that stay on the plant for a long time. Rather than petals, most flowers are made of thin and papery parts that look more like scales or sometimes sepals, and they sometimes remain attached to the fruits as they grow, developing into wings, spines, or bumps to help protect or distribute them.

Reproductive Features of the Amaranthaceae: These are very diverse in the family, ranging from flowers with both male and female parts (bisexual) to separate male and female flowers on separate plants (dioecious). And since the flowers are tiny, these features are seldom easily visible, so we’ll skip it here. But you can check out the scientific botanical description below for more information.

Fruits of the Amaranthaceae: Fruits may be dry, bladder-like fruits (utricles) or capsules that may split open from the top, but sometimes they are small, fleshy berries or drupes (think cherry—fleshy with a stony pit). In some species, the fruit stays enclosed in and is dispersed with the flower parts. The seeds are known for containing starch, which helps them grow and makes them useful as a human food source.

Uses of Amaranthaceae

The Amaranthaceae family has a few cultivated ornamentals that are from Amaranthus, Gomphrena, and Iresine, and some noxious weeds are notable from Amaranthus, Iresine, and Acnida. Amaranthus species are also used as food in many parts of the world. In North America, Native American peoples used to cultivate it for both the greens, eaten as a vegetable, and the seeds, which were often ground into flour. Amaranth seeds and flour are gaining renewed interest as they make a suitable replacement for wheat for those with grain allergies and gluten intolerance. Other commercially grown species include the sugar beet and Swiss chard from Beta vulgaris and spinach (Spinacia oleracea).

Morphology of Amaranthaceae in North America

Learn how to identify the Amaranthaceae family with simple descriptions and morphology photos.

Some Amaranthaceae Species Of North America

Amaranthoideae Subfamily

Achyranthes aspera inflorescence showing conspicuous bracts characteristic of the Amaranthaceae family.

Achyranthes aspera—Chaff Flower

This is a tall herb, up to 2 m tall, with silky or short-hairy stems and variable leaves, often somewhat egg-shaped to rounded. Sessile flowers are in a long spike surrounded by persistent awned bracts and bracteoles. These pantropical herbs are introduced to the southern USA and Mexico.

Amaranthus arenicola—Sand Amaranth

This dioecious annual (male and female flowers on separate plants) is common in sandy habitats, hence its common name. It has simple leaves and grows 2 m tall. Flowers occur in congested clusters (as shown in the photo). Native to the central and south Great Plains of the United States.

Branched inflorescence of Amaranthus palmeri, branched spikes like these are characteristic of the Amaranthaceae.

Amaranthus palmeri—Palmer’s Amaranth

This species is a fast-growing, aggressive herb that grows to 1.5+ m tall with diamond-shaped leaves on long stalks. Flowers are in terminal spikes or drooping branched inflorescences, as shown in the photo. Native to southern North America but now widely introduced and considered one of the most noxious weeds in the world. It is also edible and highly nutritious and can be used as a food crop in marginal environments.

Amaranthus retroflexus plant with inflorescences

Amaranthus retroflexus—Red Root Amaranth

It is a tall herb, growing to 3 m tall; is pubescent and hairy; and has rhombic or ovate leaves with long petioles. Flowers are in terminal and axillary spikes or panicles. It is believed to be native to eastern and central North America.

Camphorosmoideae Subfamily

Bassia scoparia infructescence with leaves and immature fruits

Bassia scoparia—Summer Cypress

This annual herb grows up to 1.5 m tall and has linear–lanceolate leaves that often curl and a stem that is often reddish. Inconspicuous flowers grow in the leaf axils with much more conspicuous 0.5-1 cm long bracts. This Amaranthaceae member is a highly invasive Eurasian introduced species.

Chenopodioideae Subfamily

Atriplex canescens—Four-Wing Saltbush

This lovely woody shrub has the occasional spine on its branches, as well as plenty of more or less stalkless, somewhat oblong leaves and tiny flowers in congested spikes, as shown here. It produces conspicuous, winged greenish bracteoles that expand in fruit and turn papery and beige, becoming wings. This common Amaranthaceae member is native and widespread in the western USA.

Atriplex confertifolia Spiny Saltbush inflorescences with flowers; compact globular inflorescences are fairly common in the Amaranthaceae.

Atriplex confertifolia—Spiny Saltbrush

This one is similar to A. canescens but with shorter, wider leaves, unwinged fruits, and many more spines on its branches. It’s also native to dry areas of the western USA, especially in the Great Basin region.

Chenopodiastrum simplex leaf closeup, large leaves are not common among the Amaranthaceae family.

Chenopodiastrum simplex—Giant-Seeded Goosefoot

This herb has larger leaves than most of the family; they are 3–10 cm long and more than half as wide, with irregular, large pointy teeth, lobes, or lobules (of varying depths), mostly hairless stems and leaves, and small flowers without petals. It is native to much of North America.

Chenopodium album inflorescence with flowers

Chenopodium album—White Goosefoot

This plant is a very common erect annual with visible lines down its stems in green or reddish-purple. Their leaves are diamond-shaped to eggshaped, and their flowers are in compact cymes in terminal or lateral spikes. It was introduced from Eurasia and is widespread in North America.

Krascheninnikovia lanata infructescence with fruits and silky hairs that help them fly in the wind

Krascheninnikovia lanata—Winterfat

This is a small shrub with flat lance-shaped leaves. Leaves and stems are both white and woolly, turning reddish. Its fruits (utricles) are densely woolly and visible all winter, giving it its common name of “winterfat.” The silky hairs help them disperse in the wind. It is endemic to western North America from Canada south to northern Mexico.

Gomphrenoideae Subfamily

Froelichia floridana infructescence with fruits

Froelichia floridana—Large Cottonweed or Plains Snakecotton

A small annual with a single erect or ascending stem and leaves on the bottom third of the plant that are lanceolate to linear with silky-wooly hairs. Flowers are in hairy spikes, and the fruits are flask-shaped utricles. Native to the central and eastern USA and northern Mexico.

Gomphrena serrata—Prostrate Globe Amaranth

An erect or prostrate perennial or annual, with a pilose stem and obovate to oblong pilose leaves that are sessile to petiolate. Flowers in a head covered by white lanceolate bracteoles. Native to the southeastern USA, south to the tropical Americas.

Iresine diffuse inflorescence with flowers

Iresine diffusa—Juba’s Bush

This is a branched erect to clambering annual to perennial with elongated egg-shaped leaves that are 3 – 14 cm long and hairless to woolly-hairy. Flowers are in woolly-hairy branched open inflorescences (males) or compacted ones (females). This species is native to South America and has been introduced into North America.

Salsoideae Subfamily

Halogeton glomeratus plant without flowers

Halogeton glomeratus—Salt Lover

This well-branched annual has narrow fleshy blue-green leaves tipped with long spines and flowers that grow densely along the branches with large, conspicuous, waxy, winged bracts. This species is native to Central Asia and introduced in western North America. It is often easy to spot because it is a halophyte, or salt-loving species that grows where many other plants cannot.

Salsola tragus in fruit. This introduced Amaranthaceae species is one of our most common tumbleweeds.

Salsola tragus aka Kali Tragus—Tumbleweed

This is a low-growing annual with branched and tangled stems and firm, more or less linear & usually very spine-tipped leaves. Flowers are surrounded by long spiny bracts and a disk of winged white/pink sepals. This Amaranthaceae member is from Russia and widely introduced in western North America. It is often our most common tumbleweed, breaking easily at the base when mature to roll across the plains and disperses its seeds.

Scientific Botanical Description of the Amaranthaceae

Habit & Leaf Form of Amaranthaceae

Most are annual or perennial (sometimes biennial) herbs or subshrubs, some shrubs, and a few vines and small trees. Sometimes they are succulent and nearly always halophytic in the Chenopodioideae, where they can even be more or less cactoid with succulent photosynthetic stems (Salicornia). Many species have thickened nodes on their stems. The wood of the perennial stem has a typical anomalous secondary growth, and only the subfamily Polycnemoideae has normal secondary growth.

Leaves may be well-developed, much reduced, or absent, and they may be minute to large in size. Usually they have no basal aggregation of leaves except sometimes in Ptilotus and the Chenopodioideae. The leaves are arranged alternate or opposite, and they are usually herbaceous but can also be fleshy or membranous. They are simple and may be petiolate or sessile, connate or not, sheathing or not, and flat or terete, and they are exstipulate and epulvinate. Leaves can be extremely variable in shape, but they mostly have entire or occasionally toothed margins. The lamina is either one-veined or pinnately veined. Various hair shapes and features are often present, and domatia are common.

Flowers of Amaranthaceae

Plants are usually hermaphroditic but otherwise may be monoecious, andromonoecious, gynomonoecious, dioecious, androdioecious, or rarely polygamomonoecious. Flowers are solitary, paired (axillary), or aggregated in terminal or axillary cymes, spikes, heads (often with conspicuous persistent bracts and bracteoles), panicles, or thyrses, and they may or may not be pseudanthial. Flowers are small to minute in size; they are bracteate and bracteolate, regular, and tricyclic when hermaphrodite; otherwise, sometimes, they are cyclic or two-cyclic. Free hypanthium is usually absent except sometimes in the Chenopodioideae. The hypogynous disk is absent except in Chenopodioideae, where it is usually present. The perianth is dry and scarious, sepaloid or petaloid, or may be vestigial or absent (sometimes in Chenopodioideae). When present, there are 3–5 (1–6) parts to the perianth. The perianth is typically interpreted as a calyx with 3–5 (1–6) parts that may be free, partially connate, or connate (almost always in Chenopodioideae). The calyx is regular, imbricate, usually non-fleshy except in Chenopodioideae, persistent in fruit, and may or may not be accrescent, enclosing the fruit with wings, tubercles, or spines.

Androecium of Amaranthaceae

The androecium has 2-5 (1–10) members that are either free of the perianth or adnate to the perianth or disk. All members are usually unequal except in the Chenopodioideae and some Ptilotus, where they are all equal. They are always in one whorl and are usually basally coherent, 1 adelphous, with filaments usually connate all or part of their length into a membranous tube, or in Chenopodioideae, they are often free from one another. The androecium can be made of exclusively fertile stamens (sometimes, or usually, in Chenopodioideae) or may often include staminodes, with some members lacking anthers or with petaloid or pseudostaminodial scales alternating with the true androecial members. When present, there are 1–3 or 5 staminodes in the same series as fertile stamens, and they may or may not be petaloid. There are 3-5(1) stamens that are oppositisepalous and usually isomerous with the perianth. The anthers dehisce via longitudinal slits, and they are introrse, unilocular to bilocular, and either bisporangiate or tetrasporangiate.

Gynoecium of Amaranthaceae

The gynoecium is 2–3(4–5) carpelled, often 5 carpelled in Chenopodioideae, and the pistil is 1-celled. The gynoecium is synovarious, synstylovarious, or syncarpous, and it is usually superior but can sometimes be partly inferior. The ovary is 1-locular and sessile to stipitate. The gynoecium may be non-stylate or stylate. When present, there are 1-3 (2-4) styles that may be partially joined. There are 1-3 stigmas (1-3) that are of the dry type, papillate, and Group II type. Placentation is always basal. There are 1-2 or 5 ovules in the single cavity, and they are ascending or pendulous, non-arillate, campylotropous, bitegmic, and crassinucellate.

Fruit of Amaranthaceae

The fruit may be fleshy or non-fleshy. It may be a dehiscent, irregular, or often circumscissile capsule, or it may be an indehiscent berry, drupe, nut, capsule, or, often, a utricle. Sometimes in the Chenopodioideae, the fruit may be enclosed in the fleshy hypanthium or perianth, and sometimes, the gynoecia also combine to form a multiple fruit. Seeds are non-endospermic and contain starch. Perisperm is present (abundant, mealy) or sometimes absent in Chenopodioideae. Seeds have starch.

Taxonomy of Amaranthaceae

There are currently about 2000 – 2500 species in about 180 accepted genera of the Amaranthaceae family, which is part of the Caryophyllales order of core eudicots. There are currently 6–10 subfamilies, as this family is being reworked. Here I describe it with the 10 divisions I had, which APG shows in their list of genera, even though on the website it shows several have become tribes instead. Once the family work is complete, I will update the list again, but for now it reflects the most current data I have (May 5, 2026).

Amaranthoideae – Annual or perennial herbs to shrubs, occasionally small trees. The inflorescence is branched or not but is usually spike-like or capitate. The bracts are disarticulating, and bracteoles may or may not be papyraceous or scarious. The perianth is typically scarious, and it possesses staminodes or pseudostaminodes. Cuticle waxes lack platelets, and hairs are uniseriate.
Betoideae – Annual to perennial herbs or occasionally subshrubs or vines. Bracteoles are usually present; the perianth has 5 (3) parts and is persistent and accrescent in Beta. The androecium has 5 (1) members, and the gynoecium is sometimes partly inferior. The fruit is a circumscissile capsule or pyxidium.
Camphorosmoideae – Often shrubby plants but sometimes annual herbs, often with C4 photosynthesis; leaves are terete, and ‘prickles’ are often present. Their hairs have swollen bases, styles are filiform with papillae all around. The perianth is fleshy and spiny.
Chenopodioideae – Annual herbs or short-lived perennial herbs to shrubs that are more or less succulent and often have swollen nodes. They prefer dry and/or saline temperate to subtropical habitats. Flowers are small and have a greenish perianth that often becomes more elaborate after flowering and is accrescent with the usually indehiscent fruits.
Corispermoideae – Annual herbs without C4 photosynthesis. The inflorescence is spicate, simple, compact, or sometimes globular, and lacking bracteoles. Leaves are mostly alternate, sessile, or petiole-like. Hairs are branched or stellate. Perianth has 0-5 membranous tepals that are not persistent.
Gomphrenoideae – Annual to perennial herbs or subshrubs with a perianth that is free to connate. Anthers are bisporangiate, monothecal, and their filaments are more or less connate. Their stigma is either capitate or bilobed.
Polycnemoideae – Annual to perennial herbs or small shrubs that often inhabit saline habitats. Leaves are needle-like or succulent, bracts are disarticulating, and bracteoles are large. Flowers are axillary, the perianth is petaloid but never modified, and the androecium is basally connate. This subfamily is distinguishable from all other members of Amaranthaceae by normal secondary growth.
Salicornioideae – Annual or perennial herbs to low shrubs, usually with articulated stems. Plants are glabrous, and leaves are usually opposite, more or less terete or scaly or reduced to a rim. The inflorescence is dense, spicate, and leafless. The perianth has 3-4 (2-5) parts and is typically at least partially connate. In fruiting, the perianth may remain membranous or become spongy, crustaceous, or horny.
Salsoideae – Herbs, subshrubs, shrubs, or sometimes trees. Stems and leaves are often succulent, leaves are terete, and bracteoles are present. Scarious wings usually develop from the perianth in fruit. Anthers have colored appendages, and their stigmas are flattened.
Suaedoideae – Annual to perennial herbs to shrubs that are usually glabrous and usually have well-developed terete leaves. The inflorescence is spicate axillary cymes that are loose, leafy, and possess bracteoles. Styles are filiform; stigma may be capitate but is papillate all around. The perianth is persistent and usually accrescent and enlarged or winged when in fruit.

Genera of the Amaranthaceae:

Amaranthoideae: Achyranthes (33), Aerva (7, 6 extant), Allmania (3), Allmaniopsis (1), Amaranthus (93), Arthraerua (1), Bosea (3), Calicorema (2), Celosia (46), Centema (2), Centemopsis (13), Chamissoa (3), Charpentiera (6), Chionothrix (2), Cyathula (44), Cyphocarpa (?), Dasysphaera (4), Deeringia (10), Digera (1), Eriostylos (1), Evelynastra (1), Hebanthodes (1), Henonia (1), Herbstia (1), Hermbstaedtia (14), Indobanalia (1), Kyphocarpa (4), Lagrezia (14), Lecosia (2, not in APG), Leucosphaera (1), Lopriorea (1), Marcelliopsis (3), Mechowia (2), Neocentema (2), Nothosaerva (1), Nyssanthes (4), Omegandra (1), Ouret (8), Paraerva (2), Pleuropetalum (3), Pleuropterantha (3), Polyrhabda (1), Pseudosericocoma (?), Psilotrichopsis (1), Psilotrichum (26), Ptilotus (127), Pupalia (4), Rosifax (1), Saltia (1), Sebsebea (1), Sericocoma (3), Sericorema (2), Sericostachys (2), Siamosia (1), Stilbanthus (1), Trichuriella (1), Volkensinia (1), Wadithamnus (1).

Betoideae: Acroglochin (3), Aphanisma (1), Beta (10), Hablitzia (1), Oreobliton (1), Patellifolia (1).

Camphorosmoideae: Bassia (20), Camphorosma (5), Chenolea (2), Didymanthus (1), Dissocarpus (4), Enchylaena (1?), Eremophea (2), Eriochiton (1?), Grubovia (6), Kirilowia (? = Bassia), Kochia (? = Bassia), Londesia (? = Bassia), Maireana (58), Malacocera (4), Neobassia (2), Neokochia (2), Osteocarpum (5), Panderia (?), Roycea (3), Sclerolaena (78), Spirobassia (1), Stelligera (? = Sclerolaena), Threlkeldia (2).

Chenopodioideae: Ambrina (?), Archiatriplex (1), Atriplex (250), Axyris (7), Blitum (12), Carocarpidium (?), Ceratocarpus (1), Chenopodiastrum (10), Chenopodium (133), Dysphania (47), Eokochia (1), Exomis (1), Extriplex (2), Grayia (4), Halimione (?), Holmbergia (1), Krascheninnikovia (3), Lipandra (1), Manochlamys (1), Microgynoecium (1), Neomonolepis (1), Oreosalsola (12? Not in APG), Oxybasis (14), Phyllotheca (2?), Proatriplex (1), Sclerochlamys (?), Spinacia (2), Stutzia (2), Suckleya (1), Teloxys (1).

Corispermoideae: Agriophyllum (6), Anthochlamys (5), Corispermum (75).

Gomphrenoideae: Alternanthera (107), Froelichia (15), Froelichiella (1), Gomphrena (144), Guilleminea (7), Iresine (34), Pedersenia (8), Pfaffia (33), Pseudogomphrena (?), Pseudoplantago (2), Quaternella (3), Tidestromia (6), Xerosiphon (2).

Polycnemoideae: Hemichroa (1), Nitrophila (4), Polycnemum (6), Surreya (2).

Salicornioideae: Allenrolfea (3), Arthrocaulon (3), Arthroceras (1), Halocnemum (3), Halopeplis (3), Halostachys (1), Heterostachys (2), Kalidium (8), Mangleticornia (1), Microcnemum (1), Salicornia (53), Tecticornia (48).

Salsoideae: Agathophora (1), Akhania (3), Anabasis (30), Arthrophytum (7), Brachylepis (?), Caroxylon (134), Climacoptera (39), Cornulaca (6), Cyathobasis (1), Gamanthus (5?), Girgensohnia (5), Halanthium (5), Halarchon (1), Halimocnemis (21), Halocharis (6), Halogeton (3), Halothamnus (22), Halotis (?), Haloxylon (12), Hammada (2), Horaninovia (8), Iljinia (1), Kali (? = Salsola), Kaviria (9), Lagenantha (2?), Micropeplis (1?), Nanophyton (8), Noaea (7), Nucularia (1), Ofaiston (1), Petrosimonia (11), Physandra (1?), Piptoptera (1), Pyankovia (3), Rhaphidophyton (1), Salsola (39), Seidlitzia (3?), Sympegma (2), Traganopsis (1), Traganum (2), Turania (4? Not in APG).

Suaedoideae: Baolia (1), Bienertia (4), Fadenia (1?), Suaeda (94).

Key Differences From Similar Families

Amaranthaceae differs from the similar but very small (only two genera) Achatocarpaceae family because Amaranthaceae usually have a herbaceous habit vs. always being woody and always with normal secondary growth in Achatocarpaceae. Amaranthaceae also usually have dry fruits rather than the succulent berries found in the Achatocarpaceae.

Distribution of Amaranthaceae

The Amaranthaceae family is a temperate to tropical, truly cosmopolitan family missing only from Antarctica and the most extreme Arctic areas. Widespread throughout North America, Central America, the Caribbean, and South America.

Distribution of Amaranthaceae in the Americas

Canadian Amaranthaceae Genera Include:

Amaranthoideae: Achyranthes 1 sp. intro in ON; Amaranthus 20 spp. intro in BC, NT, NB, NS, PE, and NL Island, with some native in AB, SK, MB, ON, and QC. Camphorosmoideae: Bassia 2 spp. intro to all S provinces except NL, NS, and PE. Chenopodioideae: Atriplex 18 spp. native to all of Canada and Greenland; Axyris 1 sp. intro to all of S Canada exc PE and NL; Blitum 4 spp., including 2 native and 2 intro in all of Canada inc Arctic but ephemeral PE and NL (exc Labrador); Chenopodiastrum 4 spp. inc 1 native to all S provinces exc NL and 3 spp. intro into S Canada, YT, and NT; Chenopodium 19 spp. native to YT, NT, BC, AB, SK, MB, ON, QC, and NS, and intro in NB, PE, NL, NU (and Greenland); Dysphania 4 spp., including 3 intro to BC, ON, QC, NB, and NS and 1 native to ON, QC, and MB; Krascheninnikovia 1 sp. native to YT, AB, SK, and MB; Lipandra monospecific intro to BC, SK, MB, ON, QC, and NB; Oxybasis 6 subcosmopolitan spp. including 3 native to all of Canada including the Arctic but excluding PE and NL, and 3 spp. intro to E Canada; Spinacia 1 sp. intro and ephemeral in YT, NT, AB, and MB; Stutzia 1 NW NAM endemic sp. native to AB and SK; Suckleya monospecific N-C NAM endemic sp. native to AB and SK. Corispermoideae: Corispermum 6 spp., mostly native to BC, AB, SK, MB, ON, QC, YT, and NT. Gomphrenoideae: Froelichia 1 sp. intro to ON. Polycnemoideae: Polycnemum 3 spp. intro to BC and ON. Salicornioideae: Salicornia 5 spp. native to all of Canada except Labrador, it’s found in coastal and inland saline areas. Salsoideae: Salsola (inc. Kali) 3 spp. intro to all S provinces. Suaedoideae: Suaeda 4 spp. native to all of Canada except for Labrador.

USA Amaranthaceae Genera Include:

Amaranthoideae: Achyranthes 4 spp. including 2 intro to TX, LA, FL, AL, KY, WV, IN, OH, and MD, plus 2 spp. endemic to HI; Aerva 1 sp. native and believed extinct in HI; Amaranthus 45 spp. both intro and native in all of the USA, including HI and intro in AK; Celosia 4 spp., including 1 native to TX and FL and 3 intro to most of E USA from WI S to MS and all E exc MI, GA, SC, RI, MA, NH, ME, and inc MO, LA, KS, UT; Charpentiera 5 spp. endemic to HI; Digera monospecific sp. intro to NJ; Hermbstaedtia 1 sp. intro to MD. Betoideae: Aphanisma monospecific SW NAM endemic sp. native to CA; Beta 2 spp. intro to MT, OR, CA, UT, TX, MO, AL, SC, NC, VA, WV, PA, MI, NY, CT, MA, RI, NH, and ME. Camphorosmoideae: Bassia 6 spp. including 2 native and 4 intro to most of the USA except AR, GA, and FL, and intro to HI; Enchylaena 1 sp. intro to CA; Neokochia 2 W USA endemic spp. of OR, CA, ID, NV, MT, WY, CO, UT, AZ, NM, and TX; Spirobassia monospecific intro to PA, NJ, MD, NY, and CT. Chenopodioideae: Atriplex 94 spp. mostly native with some intro, found in most of the USA, including AK, but excluding AR and TN, and intro HI; Axyris 1 sp. intro to MT, CO, ND, WI, and MO; Blitum 4 spp. inc. 3 native and 1 intro to most of USA except AR S to LA and E to NC S to FL plus VA, MD, and DE; Chenopodiastrum 2 spp. including 1 native to most of the USA and AK but excluding OR, AZ, AL, GA, SC, and FL where intro and 1 sp. intro scattered throughout USA; Chenopodium ~40 spp. native and intro to all of the USA inc AK and HI; Dysphania 11 spp. native and intro to the entire USA, intro in AK and HI; Extriplex 2 SW NAM endemic spp. native to CA, inc 1 narrow endemic; Grayia 4 W USA endemic spp. from MT S to NM and all W; Krascheninnikovia 1 spp. native to W USA from ND S to TX and all states W; Lipandra monospecific sp. intro to OR, WI, IL, MI, PA, NJ, NY, CT, and ME; Neomonolepis monospecific former SW NAM endemic of CA, NV, and OR; Oxybasis 6 spp., including 2-3 native to most of USA except the SE states and 2-3 spp. intro to much of the same range but including FL, AL, IL, IN, KY, WV, VA, NC, and VT; Proatriplex monospecific S-C USA endemic of UT, AZ, CO, and NM; Spinacia 1 sp. intro to WA, OR, CA, UT, TX, KS, SC, NC, VA, OH, PA, CT, MA, NY, NH, and ME; Stutzia 2 NW NAM endemic spp. native to CA, NV, MT, WY, CO, ND, SD, and NE; Suckleya monospecific N-C NAM endemic sp. native to MT, ND, WY, CO, NM, AZ, NE, OK, and TX; Teloxys monospecific sp. intro to MI, NY, and AK. Corispermoideae: Corispermum 9 spp. native and intro in most of the USA except ME, VT, NH, PA, MD, DE, WV, VA, TN, NC, SC, LA, MS, AL, and FL, and it is native in AK and extinct in CA. Gomphrenoideae: Alternanthera 11 spp. including 1 native to FL and the rest intro to CA, AZ, NM, TX, OK, MO, AR, LA, IL, KY, TN, MS, AL, GA, SC, NC, VA, MD, PA, NJ, NY, and HI; Froelichia 6 former Americas endemic spp. native to most of the USA except WA, OR, ID, MT, NV, UT, ND, VT, RI, and ME, including 2 narrow endemics of TX, and intro CA?; Gomphrena 8 spp. native to AZ, NM, TX, LA, FL, GA, and VA, and intro to PA, MD, OH, NY, MA, and HI; Guilleminea 1 sp. native to CA, AZ, NM, TX, OK, CO, SC, MD, AR, and LA; Iresine 6 former Americas endemic spp. native to AZ, NM, TX, KS, OK, MO, AR, LA, IL, IN, KY, TN, MS, AL, GA, FL, SC, NC, MD, and PA and intro to HI; Tidestromia 5 S NAM & Caribbean endemic spp. native to CA, NV, UT, AZ, CO, NM, TX, LA, OK, KS, SD, MO, IL, and PA. Polycnemoideae: Nitrophila 2-3? SW NAM endemic spp. native WA, OR, CA, NV, UT, and AZ, including 1 narrow endemic of the Mohave Desert; Polycnemum 1 sp. intro to IN, NY, MD, DE, and NH. Salicornioideae: Allenrolfea 1 SW NAM endemic sp. native to OR, ID, CA, NV, UT, AZ, NM, and TX (other 2 are endemic to Argentina); Arthroceras monospecific SW NAM endemic sp. native to CA; Salicornia 5 spp. native most of the USA including AK but exc. AZ, OK, AR, TN, KY, IN, WI, WV, PA, and VT, and it’s intro in HI and MI, and extirpated IL, found in coastal & inland saline areas. Salsoideae: Caroxylon 1 sp. intro in CA; Halogeton 1 sp. intro in all of W USA from MT S to NM and all W, plus SD and NE; Salsola 6 spp. intro to all of the USA including HI; Suaedoideae: Suaeda 13 spp. intro and native to most of the USA except IA, AR, TN, WV, and VT, and it is native in AK.

Mexico Amaranthaceae Genera Include:

Amaranthoideae: Achyranthes 2 spp. inc 1 intro in all of Mexico and 1 native to S Mexico; Amaranthus ~35? spp. native through all of Mexico and intro to Mexican Pacific Is.; Celosia 3? spp. native to most of Mexico except where intro in Mex, Cd Mex, and Tlx; Chamissoa 1 Mexico & neoendemic sp. native in all of Mexico; Cyathula 2 spp. native to Nay, Jal, Col, Gro, Mch, Oax, Chp, Pue, Ver, Tab, Cam, QR, and Yuc; Lagrezia 1 sp. Mexico endemic of Nay, Jal, Col, Mch, Gro, Oax, Chp, Tab, Cam, Yuc, and QR (most of genus is Madagascar); Pleuropetalum 2 Mexico & neoendemic spp. native to N+SE+SE Mexico, Ver. Betoideae: Aphanisma monospecific SW NAM endemic sp. native to BC, BCS?, and Mexican Pacific Is.; Beta 2 spp. intro to BC, BCS, Son, and Sin. Camphorosmoideae: Bassia 2 spp. intro to BC, BCS, Son?, and Sin?. Chenopodioideae: Atriplex ~30 spp. native through all of Mexico, including Mexican Pacific Is.; Blitum 4 spp., inc. 2 native and 2 intro to BCN, BCS, Son, Sin, Chi, NL, Tam, Dgo, Zac, SLP, Gto, Qro?, and Hgo?; Chenopodiastrum 1 sp. intro to BC, BCS, Son, Sin, Nay, Jal, Col, Mch, Gro, and Oax; Chenopodium ?? spp. native throughout all of Mexico; Dysphania 8 spp., inc. 7 native and 1 intro, found in all of Mexico and intro Mexican Pacific Is.; Extriplex 1 SW NAM endemic sp. native BCN and BCS?; Krascheninnikovia 1 sp. native to N Mexico in BC, BCS, Son, Sin, Chi, Coa, NL, Tam, Dgo, Zac, Qro, Ags, Gto, and SLP; Neomonolepis monospecific former SW NAM endemic native to BCN and BCS?; Oxybasis 4 3 subcosmopolitan spp., including 2 native (1 endemic) to Chi, Coa, NL, Tam, Dgo, Zac, Ags, SLP, Gto, Qro, Hgo, Mex, Cd Mex, Mor, Nay, Jal, Col, Gro, Mch, and Oax, and 2 spp. intro to BC, BCS, Son, and Sin. Corispermoideae: Corispermum 1 sp. native to Chi, Dgo, Zac, SLP, Hgo, Gto, Qro, NL, Tam, and Coa. Gomphrenoideae: Alternanthera ~6 spp. native throughout all of Mexico; Froelichia 6 former Americas endemic spp. native in all of Mexico, including 1 narrow endemic of BCS; Gomphrena ~16 spp. native to all of Mexico; Guilleminea 2 spp. native to N+SW+C Mexico; Iresine ~20 spp. native to all of Mexico, including many endemics; Pfaffia 1-3 neoendemic spp. native to S Mexico in Nay, Jal, Col, Mch, Gro, Oax, Chp, Cam, Tab, QR, and Yuc; Tidestromia 6 NAM & Caribbean endemic spp. native to BC, BCS, Son, Sin, Chi, Coa, NL, Tam, Dgo, Gto, Qro, SLP, Hgo, and Ags, inc. 1 narrow endemic of Coa. Polycnemoideae: Nitrophila 1 s.p native to NW Mexico. Salicornioideae: Allenrolfea 1 SW NAM endemic native to BCN, BCS, Son, Sin, Chi, NL, Tam, Dgo, and SLP (other 2 spp. endemic to Argentina); Arthroceras monospecific SW NAM endemic sp. native to BC, BCS, Son?, and Sin?; Salicornia 4?spp. native to most of Mexico except Pue, found in coastal & inland saline areas. Salsoideae: Salsola ~6 spp. intro to BC, BCS, Son, Sin, Chi, Coa, NL, Tam, Dgo, Zac, Gto, Qro, and Ags. Suaedoideae: Suaeda ~17 spp. native in all of Mexico including the Mexican Pacific Is.

Neotropical Amaranthaceae Genera Include:

Amaranthoideae: Achyranthes 2? spp. including 1 intro to CAM (exc. Costa Rica), Bahamas, Turks-Caicos, Aruba, Antilles (exc. Cayman Is.), SW Caribbean, Galapagos, and tropical SAM S to Peru, Bolivia, C+SE Brazil (exc. Ecuador) plus 1 native to Cuba, parts of the Antilles, Guatemeal, Colombia, and Venezuela; Amaranthus ~45 spp. native throughout N Caribbean, Antilles, SW Caribbean, Trinidad-Tobago, CAM, all of SAM, and Galapagos, and is intro to Bermuda and Juan Fernandez Is.; Celosia several spp. are native to Guatemala, El Salvador, Honduras, Nicaragua, Panama, Cuba, Hispaniola, Puerto Rico, Bahamas, Leeward & Windward Is., Venezuela, Colombia, Ecuador, Peru, and Brazil, and are intro in Belize, Cayman Is., Galapagos, Trinidad-Tobago, C Brazil, Bolivia, NE Argentina, and Paraguay; Chamissoa 3 Mexico & neoendemic spp. of Greater Antilles (exc. Cayman Is.), CAM S through tropical SAM to N Argentina exc. French Guiana and N Chile; Cyathula 3 spp. inc 2 native to CAM, Cuba, Hispaniola, Jamaica, Trinidad-Tobago, Colombia, Venezuela, Brazil, Ecuador, Peru, and Bolivia, and 1 intro to Puerto Rico, Leeward & Windward Is, Venezuelan Antilles, French Guiana, Suriname, Guyana; Hebanthodes monospecific endemic of Peru; Herbstia monospecific E SAM endemic of E+S Brazil, Paraguay, and NE Argentina; Lecosia 2 narrow endemic spp. of E Brazil (not in APG); Pleuropetalum 3 Mexico & neoendemic spp. native to CAM, Venezuela, Colombia, Ecuador, Peru, Bolivia, and Galapagos (1 narrow endemic of Galapagos). Betoideae: Beta 2 spp. intro to Honduras, Cuba, Cayman Islands, Dominican Republic, Puerto Rico, Ecuador, N & C Chile, Juan Fernández Is., Argentina, and Uruguay. Camphorosmoideae: Bassia 1-2 spp. intro to C. Chile and N. Argentina; Maireana 1 sp. intro in N Chile, Desventurados Is. Chenopodioideae: Atriplex ~20? spp. native to Honduras, Bermuda, Antilles (exc. Windward Is.), SW Caribbean, Venezuela, Colombia, Peru, Bolivia, Paraguay, Chile, Argentina, Uruguay, and S Brazil; Blitum 1 sp. intro to N Argentina; Chenopodiastrum 1 sp. intro to Honduras, Nicaragua, Panama, Bermuda, Bahamas, Turks-Caicos, Antilles (exc. Cayman Is, Windward Is.), Venezuela, Colombia, Ecuador, Peru, Bolivia, C+E Brazil, Chile, N Argentina, and Uruguay; Chenopodium ??spp. native to Honduras, Panama, Colombia, Ecuador, Peru, Chile, Argentina, Paraguay, and S Brazil, and intro C+E Brazil, Bermuda, Bahamas, Cuba, Dominican Republic, and Trinidad-Tobago; Dysphania 15 spp. native to CAM, Bermuda, all of SAM except Ecuador, French Guiana, Suriname, and Guyana where it is now intro, also intro in the Bahamas, Antilles, SW Caribbean, Trinidad-Tobago, Galapagos, and Juan Fernandez Is.; Holmbergia monospecific C SAM endemic of Bolivia, Paraguay, Uruguay, and N Argentina; Oxybasis 5 subcosmopolitan spp., including 3 native (2 endemic) of Peru, Bolivia, Chile, and NW+S Argentina and 2 spp. intro to Argentina; Spinacia 1 sp. intro to Hispaniola and Cayman Is. Gomphrenoideae: Alternanthera ~100? spp. native to Bermuda, Bahamas, Turks-Caicos, Aruba, Antilles, CAM, and all of SAM, including Galapagos, excluding S Chile; Froelichia 8 former Americas endemic spp. native to Guatemala, Honduras, Nicaragua, Cuba, Hispaniola, Jamaica, Colombia, Venezuela, Brazil, Ecuador, Galapagos, Peru, Bolivia, Paraguay, Uruguay, and N Argentina, including 4 narrow endemics of Galapagos (2), Para N Brazil, and Paraguay; Froelichiella monospecific endemic of C Brazil; Gomphrena ~90 spp. native to all of CAM and SAM, exc. S Chile, plus much of the Antilles region; Guilleminea 4 spp. native to Cuba, Hispaniola, Colombia, Ecuador, Peru, Bolivia, C Brazil, Paraguay, N Argentina, and Uruguay, inc. 2 endemics of Cuba and Uruguay; Iresine ~20 spp. Mexico + former neoendemic natives throughout all of CAM, the Bahamas, Antilles (exc. Aruba and Netherlands Antilles), and tropical SAM to N Argentina (exc. French Guiana and N Chile); Pedersenia 8 neoendemic spp. of Honduras S to Colombia, Venezuela, Ecuador, Peru, Paraguay, and N Brazil, plus Puerto Rico and the Windward Is.; Pfaffia 33 neoendemic spp. native to S Mexico, Haiti, Leeward & Windward Is., Venezuelan Antilles, Trinidad-Tobago, Costa Rica, and tropical SAM S to N Argentina (except N Chile); Pseudoplantago 2 SAM endemic spp. endemic to Venezuela (1) and S Brazil + NE Argentina (1); Quaternella 3 Brazil endemics exc. N Brazil; Tidestromia 1 S NAM & Caribbean endemic spp. native to the Dominican Republic; Xerosiphon 2 spp. endemic to most of Brazil except the south. Polycnemoideae: Nitrophila 2 SAM endemic spp. native to Argentina and N. Chile. Salicornioideae: Allenrolfea 2 Argentina endemic spp. native to all of Argentina; Heterostachys 2 neoendemic spp. native to Hispaniola, Colombia, Venezuela, Paraguay, and Argentina, including 1 narrow endemic of Buenos Aires, Mendoza & Rio Negro, Argentina, at the N limit of Patagonia; Mangleticornia monospecific endemic of Ecuador and Peru; Salicornia 5-6 spp. native in coastal and inland saline areas of the Bahamas, Turks and Caicos, Antilles (exc. Windward Is.), Colombia, Venezuela, Ecuador, Peru, Bolivia, Paraguay, S Brazil, Argentina, Chile, and Uruguay. Salsoideae: Salsola 2-3? spp. intro to Uruguay, C+S Chile, and Argentina. Suaedoideae: ~7-10 spp. native to the Bahamas, Turks and Caicos, Cuba, Hispaniola, Leeward Is., Peru, Bolivia, Chile, and Argentina, and extinct or extirpated Juan Fernandez Is.

Patagonia Amaranthaceae Genera Include:

Amaranthoideae: Amaranthus 4 spp. native to C+S Argentina, C+S Chile. Betoideae: Beta 1 sp. intro to C Chile and S Argentina. Camphorosmoideae: Bassia 1 sp. intro to C Chile and S Argentina. Chenopodioideae: Atriplex 1 sp. native throughout Patagonia and intro to Falkland Islands; Blitum 2 spp. inc. 1 intro and 1 endemic to Patagonia; Chenopodiastrum 1 sp. intro C+S Chile and S Argentina; Chenopodium 1 sp. native throughout Patagonia; Dysphania 1 sp. native to all of Patagonia; Oxybasis 4 subcosmopolitan spp., inc. 3 native to C+S Chile, S Argentina, and Falkland Islands, and 1 sp. intro to Patagonia. Gomphrenoideae: Alternanthera 1 sp. native just N of Patagonia in the mountains N of Bahia Blanca, S Argentina; Gomphrena 1-2 spp. native to S Argentina. Polycnemoideae: Nitrophila 1 SAM endemic sp. of S Argentina near N limit of Patagonia. Salicornioideae: Allenrolfea 1 Argentina endemic sp. native to S Argentina; Heterostachys 1 sp. is a narrow endemic of Buenos Aires, Mendoza & Rio Negro, Argentina, at the N limit of Patagonia; Salicornia 2? spp. native throughout all of Patagonia in salt marshes and lagoons. Salsoideae: Salsola 1? sp. intro throughout Patagonia. Suaedoideae: Suaeda 1 spp. native throughout Patagonia and the Falkland Islands.

Additional Information and References

Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, as well as personal observations in North America.
Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
Delta: Watson, L., and Dallwitz, M.J. (1992+). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
Flora of North America (FNA) (1993+). https://floranorthamerica.org/Main_Page.
GBIF.org (2020), GBIF Home Page. Available from: https://www.gbif.org
Naturalista: CONABIO http://www.naturalista.mx (Accessed 2020–current).
Neotropikey: Milliken, W., Klitgård, B., & Baracat, A. eds. (2009+). Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
POWO (2019). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet: http://www.plantsoftheworldonline.org/
Stevens, P. F. (2001+). Angiosperm Phylogeny Website. Version 14, July 2017 [more or less continuously updated since]. http://www.mobot.org/MOBOT/research/APweb/
USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; accessed throughout the fall of 2020.
WFO (2022): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

My Current Plant Family Education Fundraiser

I am currently seeking funding to expand my website and SEO capabilities as I keep adding new families, and I am also looking to invest in a new macro lens, as I will soon be adding floral dissections to the families as they become available to me. You can donate to help support native plant education using the GoFundMe link, also at the bottom of the page.

Copyright Information

The information and the photos on this site are free to use for educational purposes, with proper attribution. For other uses, please contact me first.

You can cite this site as follows: Willis, Lyrae (2020+). Lyrae’s Nature Blog – Plant Families of North America. https://lyraenatureblog.com/. Accessed [Enter Date].

25 Sep, 2022

18 Sep, 2022

Identify the Anacardiaceae—Cashew/Sumac Family

Rhus typhina Staghorn Sumac plants with fruits (drupes). Learn how to identify the Anacardiaceae family with morphology photos. — *Rhus typhina* Staghorn Sumac plants with fruits (drupes).
Page Last Updated May 3, 2026.

Introduction to the Anacardiaceae Family

The Anacardiaceae family is part of the Sapindales order of core dicots. When you learn to identify the Anacardiaceae family, you will quickly learn its most well-known members in North America, the sumac (Rhus spp) and poison ivy (Toxicodendron spp). The sumac trees are often used ornamentally for their ease of growing and their pretty red drupes that persist all winter. Poison ivy is well known to anyone who has ever hiked in the forest since it causes very itchy contact dermatitis.

There is an old saying, “Leaves of three, let it be,” since all of the Toxicodendron species that cause poison ivy rash have trifoliate leaflets. It is a good rule of thumb if you are unsure of your plant ID. But be aware that numerous innocuous species exist that also have trifoliate leaves, so do not assume it is always poison ivy. Poison ivy (shrub form) can also be mistaken for young oaks at times because the leaves often resemble those of the white oak.

Common Botanical Description

If you’re new to plant morphology, this is a perfect beginner’s description to learn to identify the Anacaradiaceae family, with no need to know any scientific jargon. For researchers or those wanting to learn a more in-depth version, check out the Scientific Botanical Description below.

Leaves and Stems: Mostly woody shrubs and trees or climbing vines with resin canals in their leaves, roots, and stems that often release a milky or resinous juice when damaged and that may be aromatic. Leaves are often arranged in a spiral pattern along the stem and may be simple (1 blade) or compound and made of multiple leaflets.

Flowers: These are usually quite small and occur in branched clusters called panicles. Most flowers have 5 sepals and 5 petals, but they may lack petals or they may all be more green and sepal-like. They often contain a ring-shaped nectary inside to attract pollinators.

Reproductive Features: These are quite diverse in the family, with bisexual flowers that contain both male and female parts or separate male and female flowers that may be on the same (monoecious) or separate plants (dioecious). There are usually 5-10 stamens and a superior ovary (sits above the point of petal attachment) with 1 or up to 6 styles (the tube that collects pollen) on top.

Fruits: The fruit is usually a fleshy drupe (think cherry but usually smaller) containing a fleshy outer part and a single hard pit. The fruits and sap of some species contain urushiol, the toxic oil responsible for the skin irritation of poison ivy (Toxicodendron species).

Uses of Anacardiaceae

Some Anacardiaceae are edible plants, such as cashew nuts (Anacardium and the fleshy peduncle of the cashew apple), mango (Mangifera), Jamaica plum, hog-plum, imbu (a plum-like fruit from Spondias), and Amarula cream (from Sclerocarya typically made into a liqueur). Resins, oils, and lacquers are derived from Toxicodendron. Several non-native Anacardiaceae are cultivated in the Neotropics for their edible fruits, including Bouea macrophylla,, Harpephyllum caffrum, Mangifera indica, Schinus terebinthifolia, Sclerocarya birrea subspecies caffra, and Spondias dulcis. Many Anacardiacea species are notorious for their allergenic properties that often cause severe rashes, particularly Toxicodendron spp. (Poison Oak, Poison Ivies).

Morphology of Anacardiaceae in North America

Learn to identify the Anacardiaceae family with morphology photos

Some Anacardiaceae Species I have Covered So Far

Anacardioideae Subfamily

Mangifera indica—Mango

A 10-20 m tall tree with long oblong leaves and large edible drupes on very long peduncles. Native to Asia but widely cultivated in southern North America, especially in Mexico.

Pistacia vera—Pistacio

A small to medium-sized tree up to 10 m tall with deciduous, pinnate leaves 10–20 cm long. Flowers have no petals and male and female flowers occur on separate trees (dioecious). Fruits are a drupe containing the elongated pistacio “nut.” These flowers are male.

Rhus aromatica—Fragrant Sumac

A somewhat lemon-scented shrub with trifoliate lobed leaves and hairy red drupes. Dioecious with small inconspicuous flowers. Native throughout the USA, Mexico, and southeastern Canada.

Rhus copallinum plant with flowers - note winged rachis and compound leaves; compound leaves are fairly common in the Anacardiacea family.

Rhus copallinum—Shining Sumac

A tall shrub with glossy odd-pinnate leaves that have a conspicuously winged rachis or petiolules (visible in the photo). Native to eastern North America, often cultivated.

Rhus glabra—Smooth Sumac

A tall shrub with hairless branches and odd-pinnate leaves with 11 – 31 acuminate, serrated leaflets. Produces large dense panicles of red drupes like shown in the photo. Native to eastern North America with scattered populations in western North America.

Rhus microphylla—Littleleaf Sumac

A desert shrub that often flowers before its tiny, odd-pinnate, glossy green, leathery, hairy leaves emerge. Fruits are clusters of small hairy drupes. Native to the southwestern USA plus northern and central Mexico.

Rhus trilobata—Skunkbush Sumac

Despite its pungent, bitter scent that gives it a bad rap, it is not nearly as unpleasant as a skunk. It is a shrub with trifoliate lobed leaves (shown in the pic) and flowers in catkins, and its fruits are hairy, sticky red drupes. Native to western North America, including western Mexico.

Rhus typhina—Staghorn Sumac

A large shrub with odd-pinnate leaves with 9 – 31 serrated leaflets; stems and petioles are densely red-hairy (unlike R. glabra). Native to northeastern USA and southeastern Canada.

Toxicodendron radians Eastern Poison Ivy. Plant with flowers growing on a tree.

Toxicodendron radicans—Eastern Poison Ivy

A climbing vine (sometimes a shrub) with woody stems & trifoliate shiny leaves that are usually not serrated. Flowers are small, greenish, and inconspicuous. The fruit is a gray-white drupe. Causes contact dermatitis. Native to the eastern USA and Canada.

Toxicodendron rydbergii—Western Poison Ivy

A shrub with opposite trifoliate leaves that are often asymmetrical. The fruits are white, yellow, or brown drupes that are ribbed (green like in the photo when still immature). Native throughout the USA and Canada but mostly found in the West.

Scientific Botanical Description of the Anacardiaceae

Habit & Leaf Form of the Anacardiaceae

Trees or shrubs, self-supporting or climbing, sometimes with a milky juice that may be resinous or laticiferous. Leaves are evergreen or deciduous and alternate spiral except in Bouea, where they are opposite, and may be aromatic when resinous but are otherwise odorless. They are simple or compound ternate, trifoliate, imparipinnate, or rarely paripinnate or bipinnate. Primary venation is pinnate or rarely palmate. Secondary venation is eucamptodromous, brochidodromous, craspedodromous, cladodromous, or rarely reticulodromous. If present, cladodromous venation is diagnostic for the Anacardiaceae family. Leaves are exstipulate. Lamina margins are entire. Domatia occur in 8 genera as pits, pockets, or hair tufts. Resin canals located in the inner fibrous bark and pith of the stems, roots, and leaves are characteristic of this family. Tannin sacs are very common.

Flowers of the Anacardiaceae

Plants can be hermaphroditic, monoecious, dioecious, gynodioecious, or polygamomonoecious. Pollination when heterantherous is entomophilous. Flowers are aggregated in racemose panicles. Flowers are small, regular, usually 5-merous, and either tetracyclic or pentacyclic. Free hypanthium is either absent or present but short. A hypogynous disk is present, intrastaminal and annular. The perianth has a distinct calyx and corolla or may be sepaline. The perianth has 3–5 or 6–10 parts in 1 or 2 whorls and is isomerous. Calyx has 3–5 parts in 1 whorl, is basally connate, often with cleft sepals, and lobes are shorter to longer than the tube. The calyx is regular and imbricate. The corolla, when present, has 3–5 parts in 1 whorl, is usually free but rarely can be connate basally, the lobes are longer than the tube, and it is imbricate.

Androecium of the Anacardiaceae

The androecium has 5–10(11–12) parts. Androecial members are free of the perianth and may be free of one another or sometimes coherent 1 adelphous (filaments basally connate). The members may be all equal or unequal and can be either 1 or 2 whorls. There may be 0-9 staminodes. There are 5–10 (1–12) stamens that are oppositisepalous, inserted at the base of the hypogynous disc, and are usually equal in number or twice as many as the petals. Anthers are usually dorsifixed or sometimes basifixed (Spondias), they are versatile, dehiscing via longitudinal slits, introrse, and tetrasporangiate.

Gynoecium of the Anacardiaceae

The gynoecium is usually 5-carpeled but can be 1–6 carpeled, and the pistil is 1–5 celled. The gynoecium is synovarious or synstylovarious, or rarely semicarpous. It is usually superior or sometimes partly inferior. The ovary is 1–5-locular. There is usually one style, but there may be 3–6, and in Buchanania, it has up to five styles from sterile carpels. There are 1-5 stigmas of the wet type, non-papillate, and Group IV type. Placentation, when unilocular, is parietal or basal, and when bi- or plurilocular, it is basal. There is 1 ovule per locule; it is pendulous or ascending, has either a ventral or dorsal raphe, is non-arillate, anatropous, unitegmic or bitegmic, and crassinucellate.

Fruit of the Anacardiaceae

The fruit is usually a fleshy drupe, but sometimes it is an indehiscent non-fleshy dry fruit. The drupes have one stone, rarely open at maturity, and sometimes contain urushiol, a toxic irritant found in poison ivy and other species. Seeds are non-endospermic.

Taxonomy of the Anacardiaceae Family

The Anacardiaceae have 873 species in 80 genera of the Sapindales order of core eudicots. There are two accepted subfamilies with several dissident genera in their own groups or unplaced; here I have put them all as “unplaced in a subfamily.” As APG updates these, this record will be updated to reflect any changes.

Anacardioideae – Trees or shrubs with black or colored resinous exudate and crystals are present in the xylem. Leaflets are not articulated, margins are usually entire, and the base of the petiole is often swollen. Flowers are 5(-7)-merous, the calyx is more or less connate basally, the gynoecium is typically 3-carpeled, and the stigma is dry and capitate or lobed. The fruit is a drupe that is layered with a crystalliferous endocarp.
Spondiadoideae – Deciduous trees or shrubs that typically cause contact dermatitis. Flower pedicels are often articulated, the gynoecium is 4-5(3) carpelled, and the stigma is only slightly expanded. Fruit is usually more than two-seeded (but sometimes only one), its pericarp may or may not have a lacuna, and the inner mesocarp is made of encircling fibers.
“Unplaced” includes the Sclerocarya complex of multiple genera, plus Buchanania and Campnosperma, which are grouped together, and some completely unplaced ones, including Attilaea, Haplospondias, Koordersiodendron, and Pentaspadon.

Genera of the Anacardiaceae:

Anacardioideae: Abrahamia (34), Actinocheita (1), Amphipterygium (5), Anacardium (13), Androtium (1), Apterokarpos (1?), Astronium (11), Baronia (1), Blepharocarya (2), Bonetiella (1), Bouea (3), Campylopetalum (1), Cardenasiodendron (1), Comocladia (27), Cotinus (7), Dobinea (2), Drimycarpus (4), Euroschinus (9), Faguetia (1), Fegimanra (3), Gluta (35), Haplorhus (1), Heeria (1), Holigarna (9), Laurophyllus (1), Lithraea (3), Loxopterygium (4), Loxostylis (1), Malosma (1), Mangifera (64), Mauria (15), Melanochyla (21), Melanococca (?), Metopium (4), Micronychia (10), Mosquitoxylum (1), Myracrodruon (2), Nothopegia (10), Ochoterenaea (1), Orthopterygium (1), Ozoroa (45), Pachycormus (1), Parishia (8), Pegia (2), Pistacia (12), Protorhus (3), Pseudosmodingium (5), Rhodosphaera (1), Rhus (51), Schinopsis (7), Schinus (40), Searsia (110), Semecarpus (87), Smodingium (1), Sorindeia (10), Swintonia (13), Thyrsodium (6), Toxicodendron (28), Trichoscypha (32).

Spondiadoideae: Allospondias (2), Antrocaryon (5), Choerospondias (1), Cyrtocarpa (4), Dracontomelon (9), Haematostaphis (1), Harpephyllum (1), Lannea (36), Operculicarya (9), Pleiogynium (3), Poupartia (7), Poupartiopsis (1), Pseudospondias (2), Sclerocarya (2), Solenocarpus (2), Spondias (18), Tapirira (9), Tumultivenia (1), Uniostium (1).

Unplaced in a subfamily: Attilaea (1), Buchanania (26), Campnosperma (14), Haplospondias (?), Koordersiodendron (1), Pentaspadon (6).

Key Differences From Similar Families

The Anacardiaceae differ from the similar Burseraceae by having usually alternate or sub-opposite leaves or leaflets compared to the almost always opposite leaflets of Burseraceae.

Distribution of Anacardiaceae

The Anacardiaceae family is mainly tropical to subtropical, with a few important genera found in temperate North America. They are widespread pantropically and also in the Mediterranean, eastern Asia, and the warm Americas.

Distribution of Anacardiaceae in the Americas

Canadian Genera Include:

Anacardioideae: Cotinus 1 sp. intro to ON; Rhus 5 spp. native to all S provinces except NL; Toxicodendron 3 spp. native in all S provinces except NL, and including YT.

USA Genera Include:

Anacardioideae: Cotinus 2 spp. including 1 C+E USA endemic and 1 intro to UT, TX, OK, AR, IL, MO, AL, GA, TN, KY, OH, PA, NY, MD, DE, NJ, CT, MA, VT; Lithraea 1 sp. intro CA; Malosma monospecific S NAM endemic native CA; Mangifera 1 sp. intro to FL; Metopium 1 Gulf + Caribbean endemic sp. native to FL; Pistacia 3 spp, inc native in TX and 2 intro to CA, UT, OK, AL, GA, and VA; Rhus 16 spp. native and intro in the entire US, inc. HI; Schinus 5 former SAM endemic spp. intro to CA, TX, AL, FL, and HI; Searsia 1 sp. intro to CA and AZ; Sorindeia 1 sp. intro to FL; Toxicondrendon 5 spp. native in all the USA. Spondiadoideae: Spondias 1 sp. intro to FL.

Mexico Genera Include:

Anacardioideae: Actinocheita monospecific Mesoamerican endemic of Honduras and Nay, Jal, Col, Mch, Gro, Oax, and Pue; Amphipterygium 5 Mexico & CAM endemic spp. native to most of Mexico except NW Mexico, including 2 endemics of SW Mexico (1), Dgo + Jal (1); Anacardium 1 sp. intro to Nay, Jal, Col, Mch, Gro, and Oax; Astronium 2 Mexico & neoendemic spp. native most of Mexico exc. central and NW, inc. 1 narrow endemic of Ver; Bonetiella monospecific endemic of NE Mexico; Comocladia 5 Mexico & CAM endemic spp. native in all of Mexico, inc. 3 endemic to Mexico; Cotinus 3 spp. native to Chi, Coa, NL, Tam, Dgo, Zac, Ags, Gto, Qro, and Hgo, including 2 endemics; Lithraea 1 sp. intro in Pue; Malosma monospecific S NAM endemic native BCN, BCS, Son, Sin, Chi, Coa, NL, Tam, SLP, Dgo, Zac, and Mexican Pacific Islands; Mangifera 1? sp. intro SW+SE+C Mexico; Metopium 1 Gulf & Caribbean endemic spp. native to Ver, Chp, Cam, Tab, Yuc, and QR; Mosquitoxylum monospecific N Neo endemic sp. native to S Mexico in Nay, Jal, Col, Mch, Gro, Oax, Chp, Ver, Tab, Cam, Yuc, and QR; Pachycormus monospecific endemic of BCN, BCS; Pistacia 2 sp. inc 1 native to most of Mexico except BC, BCS, Son, and Sin and 1 intro to N Mexico; Pseudosmodingium 5 spp. endemic to most of Mexico exc. SE Mexico; Rhus 15+ spp. native throughout Mexico including the Mexican Pacific Is.; Schinus 2 former SAM endemic spp. intro N and SW Mexico; Toxicodendron 4 spp. native to all of Mexico. Spondiadoideae: Spondias 3 spp. native to all of Mexico; Tapirira 2 Mexico & neoendemic spp. native SW Mexico, Pue, Ver, Cam, Tab, Yuc, and QR, including 1 endemic of Oax + Ver. Unplaced: Attilaea monospecific endemic of QR, Yuc, and Guatemala; Cyrtocarpa 3 Mexico & N neoendemic spp. native to most of Mexico exc. Ver, inc. 2 endemics.

Neotropical Genera Include:

Anacardioideae: Actinocheita monospecific Mesoamerican endemic to SC Mexico and Honduras; Amphipterygium 3 of 5 Mexico & CAM endemic spp. native to Guatemala, Honduras, Nicaragua, and NW Costa Rica; Anacardium 13 spp of former neoendemic genera native from Honduras S to Peru, Bolivia, Paraguay, S Brazil, and also in Cuba and intro to the rest of Antilles (exc. Netherlands Antilles & Aruba), Belize, and El Salvador; Apterokarpos (~Loxopterygium?) monospecific endemic to the Caatinga of NE Brazil?; Astronium 10 Mexico & neoendemic spp. native to CAM S through tropical SAM to Peru, Bolivia, NE Argentina, S Brazil, including 5 narrow endemics of Brazil (4) and Trinidad-Tobago; Cardenasiodendron monospecific endemic to Bolivia; Comocladia 24 Mexico & CAM endemic spp. native to Guatemala, Belize, Greater Antilles, and Leeward & Windward Is. with 15 single-island endemics of Jamaica (6), Hispaniola (5), Cuba (2), Dominican Republic, Haiti, and 1 extinct sp. of the Windward Is.; Haplorhus monospecific endemic to the dry inter- Andean valleys of Peru to N Chile; Lithraea 3 SAM endemic spp. of C+E+S Brazil, Bolivia, Paraguay, N Argentina, Uruguay, and C Chile, inc. 1 narrow endemic of C Chile; Loxopterygium 4 SAM endemic spp. of Venezuela, Guyana, Suriname, French Guiana, Ecuador, Peru, Bolivia, NW Argentina, and NE Brazil; Mangifera 1 sp. intro to Guatemala, Belize, Honduras, El Salvador, Costa Rica, Galapagos, Antilles (excluding Netherlands Antilles, Aruba), Venezuela, Ecuador, Peru, Paraguay, and S Brazil; Mauria 15 neoendemic spp. from Costa Rica S to Colombia, Venezuela, Ecuador, Peru, Bolivia, and NW Argentina; Metopium 4 Gulf & Caribbean endemic spp. native to Guatemala, Belize, Honduras, Bahamas, Turks and Caicos, Antilles (except Leeward Is. & Venezuelan Antilles), and the SW Caribbean; Mosquitoxylum monospecific N neoendemic of Jamaica, S Mexico, Guatemala, Belize, Honduras, Nicaragua, Panama, and Ecuador; Myracrodruon 2 SAM endemic spp. of Brazil, Bolivia, Paraguay, and N Argentina; Ochoterenaea monospecific N SAM endemic to Andean Venezuela and Colombia, and Bolivia; Orthopterygium monospecific endemic to W Peru; Pistacia 1 sp. native to Guatemala and Honduras; Rhus 1-3? spp. native to Cuba, Bahamas, Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica, and intro to Trinidad-Tobago; Schinopsis 7 SAM endemic spp. of Peru, Bolivia, C+E Brazil, Paraguay, and N Argentina; Schinus 40 former SAM endemic spp. native to Peru, Bolivia, and C+E+S Brazil and all south (absent Amazonia), and intro to Ecuador, Colombia, Bermuda, the Bahamas, Turks and Caicos, Cuba, the Dominican Republic, Puerto Rico, Trinidad-Tobago, Venezuelan Antilles, Guatemala, and El Salvador; Semecarpus 1 sp. intro to Trinidad-Tobago; Thyrsodium 6 N SAM endemic spp. of Colombia, Peru, Bolivia, Venezuela, French Guiana, Guyana, Suriname, and N+C+E Brazil; Toxicodendron 3 spp. including 2 native to Bermuda, the Bahamas, Guatemala, El Salvador, Honduras, Nicaragua, Panama, Colombia, Venezuela, Ecuador, Peru, and Bolivia and 1 sp. intro to Cuba. Spondiadoideae: Antrocaryon 1 sp. endemic to Colombia and Amazonian N+C Brazil (rest of genera are tropical Africa); Dracontomelon 1 sp. intro to Trinidad-Tobago; Spondias 12 spp. inc 11 natives of Antilles, CAM S through tropical SAM S to Peru, Bolivia, and C+SE Brazil, and 1 sp. intro to Guatemala, Belize, Nicaragua, Panama, the Greater Antilles, Colombia, Venezuela, Guyana, French Guiana, N+SE Brazil, Ecuador, and Peru, including 6 narrow endemics of E Brazil; Tapirira 8 Mexico & neoendemic spp. native from CAM S through tropical SAM to Peru, Bolivia, Paraguay, and S Brazil, including 3 narrow endemics of Costa Rica, Colombia, and French Guiana; Tumultivenia monospecific endemic of E + WC Brazil; Uniostium monospecific endemic of Colombia, Venezuela, Guyana, and the Netherlands Antilles. Unplaced: Attilaea monospecific endemic of SE Mexico and Guatemala; Campnosperma 2 neoendemic spp. from Honduras S to Colombia, Venezuela, Ecuador, Peru, and Amazonian N Brazil (most of the genus is in Madagascar, Asia, and Australasia); Cyrtocarpa 2 Mexico + neoendemic spp. native to Colombia, Venezuela, Guyana, N+C+E Brazil, and the Netherlands Antilles.

Patagonia Genera Include:

Anacardioideae: Lithraea 1 SAM endemic spp. native to Bio Bio to Los Lagos in C. Chile; Schinus 6 former SAM endemic spp. native to the entire region.

Additional Information and References

Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, along with my own observations in North America.
Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
Flora of North America (1993+). https://floranorthamerica.org/Main_Page.
Delta: Watson, L., and Dallwitz, M.J. (1992+). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
GBIF.org (2020), GBIF Home Page. Available from: https://www.gbif.org
Naturalista: CONABIO http://www.naturalista.mx Accessed 2020–current.
Neotropikey: Milliken, W., Klitgård, B. & Baracat, A. eds. (2009+). Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
POWO (2019). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet: http://www.plantsoftheworldonline.org/ Retrieved Winter 2020-current.
USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; accessed throughout fall of 2020.
WFO (2022): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

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13 Sep, 2022

How to Identify the Acanthaceae Family

Introduction to the Acanthaceae Family

When you learn how to identify the Acanthaceae family, it helps to understand that it is part of the Lamiales order of core eudicots and, as such, is closely related to the Lamiaceae, or Mint family, with which it shares several characteristics. The Acanthaceae are widespread in tropical and subtropical regions, but the USA has quite a few, and they can even be found in temperate Canada. Acanthaceae are usually herbs or shrubs and typically have zygomorphic flowers in white, pink, blue, and shades of purple. Several species are used ornamentally and medicinally. In the field, if you are injured, you can crush the leaves of most Acanthaceae and apply them directly to the wounds to aid in healing.

Common Botanical Description

If you’re new to plant morphology, this guide is a perfect beginner’s description to learn about the Acanthaceae family, with no need to know any scientific jargon. Below is additional information on uses and morphology, as well as pictures to help identify family members and individual species found in North America. But for researchers or those wanting to learn a more in-depth version, check out the Scientific Botanical Description below the images in addition to genus-level distribution data.

Leaves and Stems of the Acanthaceae: Most members are tropical herbs, shrubs, or climbing vines that twine in a clockwise direction. Leaves are mostly simple (not compound) and arranged in opposite pairs along the stem, which often has swollen joints (nodes). Many species have mineral crystals (cystoliths) visible in their leaves and are covered with small hairs.

Flowers of the Acanthaceae: Flowers may be small or very large and showy and are typically irregular in shape, often forming funnel-shaped flowers or two-lipped flowers where the petals are joined at the base into a tube. Flowers are almost always surrounded by large, showy, leaf-like structures called bracts, which are very characteristic of the family (excluding the Thunbergioideae subfamily, which lacks the showy bracts).

Reproductive Features of the Acanthaceae: Most flowers contain both male and female parts (hermaphrodite or bisexual), with 2-4 stamens (male parts) attached inside the petal tube, often accompanied by smaller, sterile “fake stamens” (staminodes). The superior ovary (attached above the point of petal attachment) has a long, thread-like tube (style) on top to catch pollen and a nectary at the base to attract pollinators.

Fruits of the Acanthaceae: Fruits are almost always a dry, 2-chambered capsule that usually splits explosively when dry to scatter its seeds via small, hooked stalks (retinacula) attached to the seeds that aid in their ejection from the fruit.

Uses of Acanthaceae

The leaves of many Acanthaceae are used externally for wounds. Research has shown that the family has antifungal, anti-inflammatory, antipyretic, antioxidant, insecticidal, immunomodulatory, anti-platelet aggregation, and antiviral potential. More research is currently underway. Notable ornamentals include bear’s-breech (Acanthus mollis), clock vine (Thunbergia), shrimp plant (Justicia brandegeana), and caricature plant (Graptophyllum pictum).

Morphology of Acanthaceae in North America

Learn to identify the Acanthaceae family with Morphology photos of the Acanthaceae Family — Morphology of the Acanthaceae Family

Acanthaceae Species I have Covered So Far in North America

Acanthoideae Subfamily

Acanthus mollis flowers and bracts; these leafy bracts are very typical of the Acanthaceae family.

Acanthus mollis—Bear’s Breeches

A clump-forming perennial herb with tuberous roots, a basal rosette of deeply lobed leaves, and tall spikes of pinkish or purplish flowers. Native to the Mediterranean, often cultivated in North America for its leaves and flowers.

Carlowrightia arizonica flower and leaves

Carlowrightia arizonica – Arizona Wrightwort

Heavily branched subshrubs are 10–30 cm tall, or sometimes taller. Leaves are simple, opposite, and variable in size and shape but approximately lanceolate. Flowers are narrowly triangular with 2 lateral petal lobes, 2 upper lobes fused together with a yellow spot and purple streaks, and a keeled bottom lobe. Native to Texas, Arizona, California, and northern Mexico.

Dicliptera resupinata two-lipped flowers, a common floral form in the Acanthaceae family.

Dicliptera resupinata—Arizona Foldwing

Erect herb up to 60 cm tall with heavily branching pubescent stems; leaves are lanceolate, 2 – 6 cm long. Flowers are two-lipped, light purple with small dark purple lines near the center, and surrounded by two heart-shaped bracts. Native to southern AZ and NM, United States, and northwest Mexico.

Justicia pilosella plant with flower, Carlsbad National Park

Justicia pilosella—Hairy Tubetongue

Herbaceous perennial to 30 cm tall with opposite leaves that may be pubescent or glabrous but with ciliate margins and zygomorphic sessile flowers with a long, white, pubescent tubular corolla with 4 pink or purple lobes, 3 of which bend outwards strongly. Narrowly endemic to southern TX and southern NM in the USA, plus arid northeastern Mexico.

Ruellia blechnum Green Shrimp Plant showing flower and leafy green bracts so typical of the Acanthaceae

Ruellia blechum—Green Shrimp Plant

Short herbaceous erect or clambering perennial with opposite ovate leaves and a conspicuously pyramidal-shaped inflorescence with often pilose pyramidal bracts from Paco’s Nature Reserve, Sinaloa, Mexico; conspicuous inflorescence spike with pyramidal bracts. Native to Mexico, Central & South America.

Ruellia caroliniensis plant with flower Mammath Cave National Park

Ruellia caroliniensis – Carolina Wild Petunia

Unbranched herbaceous perennial to 1 m with opposite, oval leaves and sessile axillary clusters of 2 – 4 flowers with usually only 1 – 2 open at a time; leaves and flowers are crowded together at the top of the plant. Flowers are light purple to pinkish with a slender corolla tube and 5 petaloid lobes and long-pointed calyx lobes. Native throughout the eastern USA.

Ruellia humilis – Wild Petunia

Perennial herb up to 60 cm tall with tubular, bell-shaped flowers with a long, skinny white tube and five shallow rounded lavender to lilac-colored petals; singly or in clusters in upper axils, not crowded at the top of the plant. Native to the eastern and central USA.

Ruellia nudiflora plant with showy bractless flowers

Ruellia nudiflora – Violet Wild Petunia

An erect, 30 – 60 cm tall perennial with few branches and opposite gray-green leaves 5 – 12 cm long with wavy-toothed margins on short petioles. Terminal inflorescence of lavender to purple trumpet-shaped flowers (bractless, hence “nudiflora”) with inserted stamens. Native to the southern USA (AZ east to AL), Mexico, and Central America.

Ruellia strepens plant with flower in the Tallgrass Prairies

Ruellia strepens – Smooth Wild Petunia

An herbaceous perennial plant 0.5 – 1 m tall, sometimes branching with hairless or sparsely hairy stems; opposite leaves up to 13 cm long, lanceolate to ovate with smooth or slightly undulate margins and mostly hairless surfaces. Nearly sessile flowers in clusters of 1 – 3 in upper axils. Native to the south-central & southeast USA.

Tetramerium nervosum inflorescence with showy bracts and flower also typical of the Acanthaceae.

Tetramerium nervosum – Hairy Fournwort

Subshrub to 30 cm tall with opposite lanceolate leaves. Flowers in conspicuous pilose leafy bracts on hairy, 4-sided spike inflorescences; tubular with an upper lobe with a violet patch and a yellow base, 2 side lobes, and a keel-like lower lobe. Native to AZ and TX, USA, and south through Mexico and Central America to Venezuela.

Nelsonioideae Subfamily

Elytraria imbricata purle scaly stem plant with flowers from Sinaloa, Mexico

Elytraria imbricata – Purple Scaly Stem

Weedy subshrub with linear leaves crowded at the top of the plant that may be basal and stemless or up to 60 cm tall. Inflorescences with very appressed bracts, blue flowers. Native from the southern USA to northern Argentina, mostly in dry tropical forests.

Thunbergioideae Subfamily

Thunbergia grandiflora showy flower closeup

Thunbergia grandiflora – Blue Trumpet Vine

A twining evergreen vine 2 – 2.5 m long, with large, heart-shaped, bright green leaves and large, showy, lavender-blue, trumpet-shaped flowers up to 7 cm across with a yellow or white throat. Native throughout Southeast Asia. Often cultivated as an annual in North America.

Scientific Description of the Acanthaceae

This section is for researchers or others wanting a more in-depth scientific description to learn how to identify the Acanthaceae family.

Habit & Leaf Form of the Acanthaceae

Mostly tropical herbs, shrubs, or twining vines, with some epiphytes or rarely trees (with pneumatophores and sometimes stilt roots in Avicennia). Leaves are usually well developed but sometimes are much reduced, or occasionally plants are aphyllous switch plants. Leaves may be heterophyllous or isophyllous and are often swollen at the nodes. Branches are terete to angular in cross-section. Herbs are annual or perennial, with or without a basal aggregation of leaves. Most plants are self-supporting but may also be epiphytic or climbing as stem twiners, root climbers, or scramblers with twiners twining clockwise. Tree forms are always leptocaul. Plants may be hydrophytic, helophytic (including a few mangroves), mesophytic (many from damp tropical forests), or xerophytic. Leaves are arranged opposite distichous or decussate (rarely alternate or whorled), are simple, and may or may not be gland-dotted. The lamina is dissected or entire, pinnately veined, and cross-venulate. Leaves have no stipules. Lamina margins are entire, crenate, serrate, or dentate and may be flat, revolute, or involute. The leaf lamina is dorsiventral (sometimes incomplete) or bifacial (isobilateral in several genera), with or without epidermal salt glands, and the abaxial surface may be papillose. Stomata are almost always diacytic, but in Lepidagathis, they are paracytic; they are mainly confined to the abaxial surface. Diverse hairs are present, including eglandular, unicellular, uniseriate, glandular (may always be glandular in Nelsonioideae), and multicellular branched or simple. Cystoliths are very often present as streaks in the lamina.

Flowers of the Acanthaceae

Plants are always hermaphrodites. Pollination is entomophilous and may be conspicuously specialized. Flowers are aggregated in racemes, cymes, or verticils or often in dichasial cymes that become monochasial but are often condensed in the leaf axils; sometimes they are pseudanthial. Flowers are both bracteate and bracteolate, and they are often large and showy. In Thunbergioideae, bracts are absent, but bracteoles are present. In Nelsonioideae, bracts are present, but bracteoles are absent. Flowers are usually more or less zygomorphic, sometimes actinomorphic. Flowers are 4 or 5 merous and are tetracyclic. Free hypanthium is absent; hypogynous disk is present.

The perianth has a distinct calyx and corolla with 8(6–7) or 10 parts in 2 whorls and may be isomerous or anisomerous. The calyx has 4 (3) or 5 parts in 1 whorl, is connate, and is variously entire, lobulate, or blunt-lobed, with the lobes shorter or longer than the tube; it may be imbricate, valvate, contorted, or open in bud. When the calyx has 5 parts, the median member is free and located posteriorly. The corolla has 4 or 5 parts, or 3 parts when the upper lip is suppressed. It is 1 whorled and connate, at least basally. The corolla tube is sometimes adaxially deeply split, where the upper lip of the corolla is cut away almost to the base of the tube, making it two-lipped. The corolla is imbricate, ascending, cochlear, quincuncial, or contorted (left or right), or sometimes with open aestivation.

Androecium of the Acanthaceae

The androecium has 2 or 4 (5) members that are adnate and usually inserted on the corolla tube. They may be equal or unequal, free of one another, or coherent 2 adelphous (partially connate in pairs), and 1 whorled. The androecium usually includes 1-3 staminodes in the same series as the fertile stamens, or may be made of exclusively fertile stamens (rarely Ruellia). The stamens are usually exserted, and are usually didynamous and may or may not be hairy or spurred. Stamens are always oppositisepalous. Anthers may be separate from one another or connivent; are dorsifixed (often with one lobe reduced or abortive) or adnate, dehiscing via longitudinal slits; are unilocular to bilocular, are tetrasporangiate, and may or may not be appendaged (often with a long connective).

Gynoecium of the Acanthaceae

The gynoecium is 2-carpelled, and the pistil is 2-celled. The gynoecium is synstylovarious to syncarpous and superior. The ovary is 2-locular and sessile. The gynoecium is median. There is one terminal style that is attenuate from the ovary and usually filiform and much longer than the ovary. There are two stigmas with the posterior often smaller: they are the dry type (wet in Thunbergioideae), non-papillate (papillate in Thunbergioideae) and the Group II type. Placentation is axile with 2-50 ovules per locule that are non-arillate or arillate (occasionally with a funicular aril), anatropous to campylotropous, and unitegmic.

Fruit of the Acanthaceae

Fruit is a non-fleshy, 2-chambered loculicidal capsule dehiscing somewhat explosively or occasionally an achene (Avicennia). In most species, the seeds are attached to a small hooked stalk that helps eject them from the capsule. Seeds are non-endospermic, borne on retinacula, may be conspicuously hairy, and may contain starch.

Taxonomy of Acanthaceae

The Acanthaceae family has 4605 species in 191 genera. It is part of the Lamiales order of the Core Eudicots. There are four subfamilies of the Acanthaceae that are recognized:

Acanthoideae – herbs or sometimes shrubs, with petiole bundles arranged in a circle. Corolla often has the abaxial lobe outside others when in bud. Anthers are sagittate, or the thecae are displaced and not opposite, sometimes with one theca more or less reduced. Stigma is dry and typically bifid. Capsules are obovoid and explosive; seeds are flattened and borne on hook-like hardened funicles.
Avicennioideae – trees with pneumatophores, sometimes stilt roots. The leaf lamina is thick with salt glands on both sides, club-shaped hairs, and colleters. Flowers are 4(-6) merous and quincuncial, with nectar glands on the inside of the tube. Stamens are equal and alternate with the corolla. Stigma has two blunt lobes. Fruit is an achene with large seeds that are more or less viviparous.
Nelsonioideae – herbs with glandular hairs. The inflorescence may be terminal or axillary, bracts are spiral, and bracteoles are sometimes absent. Corolla with descending cochleate aestivation with the adaxial lobes outside the others. There are 2 stamens with variable anthers with thecae that may or may not be separate. The stigma is broadly lobed.
Thunbergioideae – twining vines, sometimes erect. Petiole bundles are arcuate or annular with wing bundles. Leaf lamina vernation is strongly curved. Inflorescence is axillary flowers or fasciculate. They have no bracts but have very large bracteoles that may or may not be connate. Anthers have lignified unicellular hairs, are sagittate, dehisce by pores or sometimes slits, and have an elongated connective. The stigma is small, wet, sub-bilobed to trumpet-shaped, and has broad and often unequal papillate lobes.

Genera:

Acanthoideae: Acanthopale (12), Acanthopsis (20), Acanthostelma (?), Acanthus (30), Achyrocalyx (?), Aechmanthera (?), Afrofittonia (1), Ambongia (1), Ancistranthus (1), Andrographis (27), Angkalanthus (1), Anisacanthus (11), Anisosepalum (3), Anisotes (29), Anthacanthus (?), Aphanosperma (1), Aphelandra (212), Aphelandrella (1?), Ascotheca (1), Asystasia (61), Asystasiella (?), Ballochia (3), Barleria (307), Barleriola (4), Blechum (1), Blepharis (128), Borneacanthus (6), Boutonia (1), Brachystephanus (21), Bravaisia (3), Brillantaisia (14), Brunoniella (6), Buceragenia (2? unplaced), Calacanthus (1), Calycacanthus (2), Camarotea (1), Carlowrightia (27), Celerina (1), Centrilla (?), Cephalacanthus (1), Chaetacanthus (1 unplaced?), Chalarothyrsus (1), Chamaeranthemum (4), Champluviera (2), Chileranthemum (3), Chlamydacanthus (3), Chlamydocardia (2), Chlamydostachya (1?), Chroesthes (4), Clinacanthus (3), Clistax (3), Codonacanthus (3), Cosmianthemum (14), Crabbea (14), Crossandra (54), Crossandrella (3), Cuenotia (1 not in APG), Cyclacanthus (2), Cylindrosolenium (1?), Cyphacanthus (1), Cystacanthus (1 unplaced?), Danguya (?), Dasytropis (1), Dianthera (41 when not inc. in Justicia), Dichazothece (1), Dicladanthera (2), Dicliptera (242), Dinteracanthus (5), Diotacanthus (?), Dischistocalyx (12), Duosperma (26), Dyschoriste (98), Ecbolium (22), Echinacanthus (4), Encephalosphaera (3?), Eranthemum (22), Eremomastax (1), Filetia (9), Fittonia (2), Forcipella (6), Geissomeria (3 unplaced?), Glossochilus (1), Golaea (?), Graphandra (1), Graptophyllum (15), Gymnostachyum (53), Gypsacanthus (1), Habracanthus (?), Haplanthodes (4), Harpochilus (3), Hemigraphis (31), Henrya (3), Herpetacanthus (21), Heteradelphia (2), Holographis (18), Hoverdenia (1), Hulemacanthus (2), Hygrophila (76), Hypoestes (139), Ionacanthus (?), Isoglossa (83), Isotheca (1), Jadunia (2), Juruasia (?), Justicia (959), Kalbreyeriella (4?), Kenyacanthus (1), Kolobochilus (?), Kosmosiphon (1), Kudoacanthus (1), Lankesteria (7), Lasiocladus (4), Leandriella (2), Lepidagathis (157), Leptosiphonium (10), Leptostachya (1), Liberatia (2 not in APG); Linariantha (1), Lindauea (?), Louteridium (11), Mackaya (5), Marcania (1), Megalochlamys (10), Megalostoma (?), Megaskepasma (1), Melittacanthus (1), Mellera (7), Metarungia (1), Mexacanthus (1), Meyenia (1), Mimulopsis (20), Mirandea (6), Monechma (14?), Monothecium (3), Morsacanthus (1), Neohallia (?), Neriacanthus (1), Neuracanthus (32), Odontonema (32), Oplonia (21), Oreacanthus (?), Orophochilus (?), Pachystachys (18), Pararuellia (11), Pelecostemon (?), Perenideboles (?), Pericalypta (1), Peristrophe (?), Petalidium (46), Phaulopsis (21), Phialacanthus (5), Phlogacanthus (42), Physacanthus (3), Podorungia (5), Poikilacanthus (13), Populina (2), Pranceacanthus (1), Pseuderanthemum (134), Pseudodicliptera (4), Psilanthele (1), Ptyssiglottis (38), Pulchranthus (4), Razisea (?), Rhinacanthus (24), Rhombochlamys (1?), Ritonia (3), Ruellia (379), Ruelliopsis (1), Rungia (87), Ruspolia (4), Ruttya (6), Saintpauliopsis (1), Salpixantha (1), Samuelssonia (1), Sanchezia (45), Sapphoa (2), Satanocrater (4), Schaueria (15), Sclerochiton (18), Sebastiano-schaueria (1), Siphonoglossa (?), Spathacanthus (4), Sphacanthus (2), Sphinctacanthus (2), Standleyacanthus (?), Stenandriopsis (20), Stenandrium (50), Stenosiphonium (?), Stenostephanus (95), Stenothyrsus (1), Streblacanthus (3), Streptosiphon (1), Strobilacanthus (?), Strobilanthes (466), Strobilanthopsis (1), Styasasia (?), Suessenguthia (8), Tacoanthus (?), Tessmanniacanthus (?), Tetramerium (31), Thysanostigma (2), Tremacanthus (?), Trichanthera (2), Trichocalyx (2), Trichosanchezia (1),Vindasia (1), Whitfieldia (13), Xantheranthemum (1), Xerothamnella (2), Yeatesia (3), and Zygoruellia (1).

Avicennioideae: Avicennia (8).

Nelsonioideae: Aymoreana (1), Elytraria (22), Nelsonia (3), and Staurogyne (155).

Thunbergioideae: Anomacanthus (1), Mendoncia (90), Pseudocalyx (6), and Thunbergia (150).

Key Differences From Similar Families

Acanthaceae are most often confused with Lamiaceae or Verbenaceae. Both the Lamiaceae and Verbenaceae usually have squarish stems as opposed to terete or angular, and their leaf nodes are not swollen. Acanthaceae has bracteoles not seen in the other two families, and their stamens are often hairy or spurred. Acanthaceae fruits are dry capsules that are often forcibly ejected as opposed to nutlets in Lamiaceae or drupes or berries in Verbenaceae.

Distribution of Acanthaceae

Acanthanceae are mostly tropical and subtropical species, with a few temperate outliers. Native throughout Africa, Australia, Indonesia, and the Americas.

Distribution of Acanthaceae in the Americas

Canadian Genera Include:

Acanthoideae: Dianthera 1 sp. native to ON and QC (s/t included in Justicia); Justicia 1 sp. native in QC and ON.

USA Genera Include:

Acanthoideae: Acanthus 1 sp. intro to CA; Andrographis 1 sp. intro to VA; Anisacanthus 4 spp. native to AZ, NM, and TX; Asystasia 1 sp. intro to FL and AL?; Barleria 2 spp. intro to FL; Carlowrightia 8 spp. native to CA, AZ, NM, and TX, and intro in FL; Dianthera 9 spp. including 8 native and 1 intro AZ, KS S to TX, and all E to NJ and S to FL from there plus IA, MI, NY, and VT (s/t included in Justicia); Dicliptera 4 spp. native to S half of USA from AZ E to NC and all S plus KS, MO, IL, IN, KY, and VA; Dyschoriste 6 spp. native to NM, AZ, TX, LA, OK, FL, AL, GA, and SC; Eranthemum 1 sp. intro to FL; Graptophyllum 1 sp. intro to FL; Hemigraphis 2 spp. intro to LA and FL; Henrya 1 sp. native to AZ; Hygrophila 6 spp. native and intro to TX, LA, AL, MS, GA, FL, and VA; Hypoestes 1 sp. intro to HI; Justicia 19 spp. native and intro in most of S half USA CA E to NJ and all S exc NV, UT, CO and inc IA, WI, MI, NY, and VT; Megaskepasma monospecific, formerly N SAM endemic, introduced in HI; Odontonema 2 spp. intro to AL and FL; Pseuderanthemum 1 sp. intro to FL and SC; Ruellia 22 spp. native in most of E half USA from ND S to TX and all E exc. ND, SD, CT, RI, MA, VT, NH, ME and including AZ and NM, but intro in AK and NY; Sanchezia 1 former neoendemic sp. intro to HI; Stenandrium 2 spp. native in NM, TX, FL, and GA; Strobilanthes 1 sp. intro LA and FL; Tetramerium 1 sub & tropical Americas endemic sp. native to NM, AZ, and TX; Yeatesia 2 SE NAM endemic spp. native to TX, LA, AL, MS, FL, and GA. Avicennioideae: Avicennia 2 of 8 pantropical spp native TX, MS, AL, GA, LA, FL, intro CA. Nelsonioideae: Elytraria 3 spp. native to NM, AZ, TX, FL, GA, and SC, including 1 narrow endemic of GA, FL, and SC; Nelsonia 1 sp. intro to FL. Thunbergioideae: Thunbergia 5 spp. intro in TX, FL, and HI.

Mexico Genera Include:

Acanthoideae: Acanthus 1 sp. intro to Pue; Andrographis 1 sp. intro to Pue, Tlx, Mor, and Ver; Anisacanthus 7 spp. native throughout all of Mexico, including 3 endemic to Mexico; Aphanosperma sinaloensis monospecific endemic to BC, BCS, Son, Sin, Chi, Dgo, Zac, NL, and Tam; Aphelandra 3-7? spp. native throughout all of Mexico; Barleria 1? sp. native to most of Mexico except BC, BCS, Son, and Sin; Bravaisia 3 Mexico + N neoendemic spp. native to much of Mexico exc BC, BCS, Son, and Sin; Buceragenia 2 unplaced narrow endemics of C Mexico; Carlowrightia 26 spp. native through all of Mexico, including 15 endemics of Mexico, 7 of which are narrow endemics of Tam (3), Chi (2), Sin, and Yuc; Chalarothyrsus monospecific endemic of Nay, Jal, Col, Mch, Gro, Oax, and Pue; Chileranthemum 3 spp. native to most of Mexico except BC, BCS, Son, and Sin, and includes 1 narrow endemic of Jal + Gro; Dianthera ?? spp. native throughout all of Mexico, s/t included in Justicia now; Dicliptera ?? many spp. native to all of Mexico; Dyschoriste ~20 spp. native throughout all of Mexico; Gypsacanthus monospecific endemic of Nay, Jal, Col, Mch, Gro, Oax, and Pue; Henrya 3 Americas endemic spp. native in all of Mexico, including 2 endemic to S+W Mexico; Holographis 18 spp. endemic genera found throughout all of Mexico; Hoverdenia monospecific endemic to Chi, Coa, NL, SLP, Dgo, Zac, and Ver; Hygrophila 3? spp. native to Nay, Jal, Col, Mch, Gro, Oax, Chp, Ver, Yuc, QR, Cam, and Tab; Hypoestes 1 sp. intro to much of Mexico exc BC, BCS, Son, Sin, Cam, Tab, Chp, Yuc, and QR; Justicia 20+ spp. native throughout all of Mexico; Lepidagathis 1-2 spp. native to Nay, Jal, Col, Gro, Mch, Oax, Chp, Pue, Mor, Ver, Cam, Tab, Yuc, and QR; Louteridium 9 Mexico + neoendemic spp. native to most of Mexico except BC, BCS, Son, and Sin, including 6 narrow endemics of Mch, Oax, Jal + Mch, Ver + Chp, Gro, and Tam; Mexacanthus monospecific endemic of Nay, Jal, Col, Mch, Gro, and Oax; Mirandea 6 Mexico endemic spp. native to most of Mexico except Pue, BC, BCS, Son, and Sin; Odontonema 4-7 spp. native in all of Mexico; Pachystachys 1 neoendemic sp. native to Chp, Cam, Tab, QR, and Yuc, and intro to Nay, Jal, Col, Gro, Mch, and Oax; Poikilacanthus 5 Mexico + neoendemic spp. native to Nay, Jal, Col, Mch, Gro, Oax, Chp, Pue, Tab, Cam, Yuc, and QR, including 4 endemic to Mexico; Pseuderanthemum 5-8 spp. native throughout all of Mexico; Ruellia ~10?? spp. native throughout all of Mexico; Sanchezia 1 former neoendemic sp. intro to Chp, Tab, Cam, Yuc, and QR; Spathacanthus 3 Mexico + CAM endemic spp. native to Nay, Jal, Col, Mch, Gro, Pue, Ver, Chp, Tab, Cam, Yuc, and QR, including 1 narrow endemic of Ver; Stenandrium 8-10 spp. native throughout all of Mexico; Stenostephanus 15 Mexico + neoendemic spp. native to most of Mexico except BC, Son, and Sin; Streblacanthus 2 Mexico & N neoendemic spp. native to Nay, Jal, Col, Mch, Gro, Oax, and Ver; Tetramerium ~25 sub & tropical Americas spp. native in all of Mexico, including 21 endemics of Mexico; Yeatesia 3 SE NAM endemic spp. native to Chi, Coa, NL, Tam, Dgo, Zac, SLP, Hgo, and Mex?, including 1 endemic of NE Mexico. Avicennioideae: Avicennia 2 spp. native to most of Mexico except C. Mexico. Nelsonioideae: Elytraria 4 spp. native to all of Mexico, inc. Mexican Pacific Is., including 2 endemics to Mexico; Nelsonia 1 sp. intro to Nay, Jal, Col, Gro, Mch, and Oax; Staurogyne 1-2? spp. native to Nay, Jal, Col, Mch, Gro, and Oax; Thunbergioideae: Mendoncia 1-2 spp. native to Nay, Jal, Col, Mch, Gro, Oax, Chp, Ver, Tab, Cam, Yuc, and QR; Thunbergia 3? spp. intro to much of Mexico except BC, BCS, Son, and Sin.

Neotropical Genera Include:

Acanthoideae: Acanthus 1 sp. intro to Costa Rica; Ancistranthus monospecific endemic to Cuba; Andrographis 1 sp. intro to Bahamas, Cuba, Hispaniola, Leeward & Windward Is.; Anisacanthus ~9 spp. native to El Salvador, Honduras, Nicaragua, Costa Rica, E Brazil, inc 5 narrow endemics of Nicaragua, Costa Rica, and E Brazil (3); Aphelandra 212 former Mexico & neoendemic spp. native from Mexico S through CAM, Trinidad-Tobago, tropical SAM S to Peru, N Argentina exc. N Chile, Paraguay, and Uruguay, and intro in Cuba, Dominican Republic, and Windward Is.; Asystasia 2 spp intro 2 Cuba, Belize, El Salvador, Honduras, Nicaragua, Antilles (exc. Netherlands Antilles), Venezuela, and SE Brazil; Barleria 1? sp. native to CAM, Colombia, Venezuela, Guyana, intro Bahamas, Antilles (exc. Cayman Is.), SW Caribbean, Trinidad-Tobago, French Guiana, and S Brazil; Barleriola 4 Greater Antilles endemic spp. of Cuba, Dominican Republic, Haiti, and Puerto Rico; Blechum 1 sp? endemic to SE Brazil; Bravaisia 3 Mexico & N neoendemic spp. native to CAM, Cuba, Colombia, Venezuela, and Trinidad-Tobago and intro to Venezuelan Antilles and Windward Is.; Brillantaisia 1 sp. intro Jamaica; Carlowrightia 4 spp. native to CAM (except Panama), and includes 1 narrow endemic in Ecuador; Cephalacanthus monospecific endemic of Peru; Chamaeranthemum 4 neoendemic spp. of Costa Rica, Peru, and SE+S Brazil, including 3 narrow endemics of Costa RIca (2) and Rio de Janeiro SE Brazil; Chileranthemum 2 Mexico + CAM endemic spp. native to Guatemala and El Salvador; Clistax 3 spp. endemic to N+E+S Brazil; Crossandra 1 sp. intro to the Antilles (except Cayman Is. and Netherlands Antilles), El Salvador, and Nicaragua; Cuenotia monospecific endemic NE Brazil; Cyphacanthus monospecific endemic of Colombia; Dasytropis monospecific endemic to Cuba; Dianthera 41 spp. now s/t included in Justicia native from E Canada & USA S through Mexico, CAM, Antilles (exc. Cayman Is & Netherland Antilles), and S through tropical SAM S to N Argentina (exc. N Chile), and intro Bermuda; Dichazothece monospecific endemic SE Brazil; Dicliptera at least 20? spp. native to CAM, Bahamas, Turks-Caicos, Greater Antilles (except Cayman Is.), Leeward & Windward Is., Trinidad-Tobago, and tropical SAM S to N Chile and N Argentina; Dyschoriste ~45 spp. native to CAM (except Belize), Cuba, Hispaniola, Venezuela, Ecuador, Peru, Bolivia, Paraguay, C+S+SE Brazil, N Argentina, and Uruguay, and intro Leeward Is.; Encephalosphaera 3 N SAM endemic spp. of Colombia, Ecuador, Peru, and N Brazil (s/t included in Aphelandra); Eranthemum 1 sp. intro to El Salvador, Antilles (excluding Puerto Rico, Netherlands Antilles, and Cayman Is.), Trinidad-Tobago, and Suriname; Fittonia 2 former N SAM endemic spp. native to Colombia, Venezuela, Ecuador, Peru, Bolivia, and N Brazil and intro to El Salvador and Trinidad-Tobago; Graptophyllum 1 sp. intro to Cuba, Hispaniola, Puerto RIco, Jamaica, Leeward Is, Venezuelan Antilles, Trinidad-Tobago, Honduras, Nicaragua, Panama, and Venezuela; Harpochilus 2 narrow endemic spp. of NE Brazil; Henrya 1 sp. native to CAM (excluding Belize); Herpetacanthus 21 neoendemic spp. of Costa Rica, Honduras, Nicaragua, Panama, Ecuador, French Guiana, Suriname, Peru, Bolivia, and N+E Brazil; Hygrophila 3-10? spp. native to Greater Antilles (exc. Cayman Is.), Trinidad-Tobago, CAM (exc. Costa Rica), and tropical SAM S to N Argentina (exc. N Chile); Hypoestes 1 sp. intro in Guatemala, El Salvador, Honduras, Panama, Colombia, and Paraguay; Isotheca monospecific endemic to Venezuela and Trinidad-Tobago; Justicia ~500 spp. native and widespread in CAM, Greater Antilles (exc. Cayman Is.), Leeward & Windward Is., Trinidad-Tobago, and tropical SAM S to N Argentina (exc. N Chile); Kalbreyeriella 4 neoendemic spp. native to Costa Rica, Panama, Colombia, N Brazil, Ecuador, and Peru; Lankesteria 1 sp. intro to Trinidad-Tobago; Lepidagathis ~50-60 spp. native to CAM, Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is, Trinidad-Tobago, tropical SAM S to Peru, NW Argentina, Paraguay, and S Brazil; Liberatia 2 SAM endemic spp. of SE+S Brazil (not in APG); Louteridium 5 Mexico & neoendemic spp. native to CAM (exc. El Salvador), including 1 narrow endemic of Belize; Megaskepasma monospecific, a former N SAM endemic of Suriname and Venezuela, now introduced in Costa Rica, Nicaragua, Panama, Trinidad-Tobago, and Comoros; Morsacanthus monospecific endemic of S Brazil; Neriacanthus monospecific endemic sp. of Jamaica; Odontonema 32 former Americas endemic spp native from Mexico S through CAM, Cuba, Haiti, Leeward & Windward Is., Trinidad-Tobago, Ecuador, Colombia, Venezuela, N+E Brazil, and Guyana, and intro Paraguay, the Dominican Republic, Puerto Rico, and Galapagos; Oplonia 16 neoendemic spp (rest of genus is Madagascar) native to the Bahamas, Turks and Caicos, Cuba, Hispaniola, Jamaica, Puerto Rico, Leeward Islands, Peru, Bolivia, and NW Argentina, including 13 narrow endemics of Cuba (8), Jamaica (3), Peru (2); Orophochilus monospecific endemic of Peru; Pachystachys 18 former neoendemic spp. native from S Mexico, Costa Rica, Panama, Cuba, Lesser Antilles (exc. Netherlands Antilles), and tropical SAM S to N Argentina (exc. Suriname, N Chile, and Uruguay), and intro Guatemala, El Salvador, Hispaniola, and Puerto Rico; Phaulopsis 1 sp. intro to Colombia and Jamaica; Phlogacanthus 1 sp intro to Windward Is.; Poikilacanthus 9 Mexico + neoendemic spp. native to Guatemala, Honduras, Nicaragua, Panama, Venezuela, Peru, Bolivia, E+S Brazil, Paraguay, Uruguay, and N Argentina, inc 6 narrow endemics of Guatemala (2), Bahia NE Brazil (1), São Paulo SE Brazil (1), Peru (1), Trujillo Venezuela (1); Pranceacanthus monospecific endemic of N+C Brazil and Bolivia; Pseuderanthemum ~60 spp. native to CAM, Colombia, Venezuela, Brazil, Ecuador, Peru, Bolivia, intro Cuba, Puerto Rico, Leeward & Windward Is., Venezuelan Antilles, and Trinidad-Tobago; Psilanthele monospecific endemic of Ecuador; Pulchranthus 4 N SAM endemic spp. of Colombia, Venezuela, N Brazil, Suriname, French Guiana, Ecuador, Peru, and Bolivia; Rhombochlamys monospecific endemic of Colombia; Ruellia ~300 spp. native to CAM, Bahamas, Turks-Caicos, Aruba, Antilles (exc. Netherlands Antilles), Trinidad-Tobago, SW Caribbean, Galapagos, and tropical SAM S to N Argentina (exc. N Chile); Ruspolia 1 sp. intro to Trinidad-Tobago; Salpixantha monospecific endemic of Jamaica; Samuelssonia monospecific endemic of Haiti; Sanchezia 55 former neoendemic spp. native to Panama, Colombia, Venezuela, N Brazil, Ecuador, Peru, and Bolivia, and now intro to Guatemala, Belize, El Salvador, Honduras, Nicaragua, Costa Rica, Antilles (exc. Cayman Is, Netherlands Antilles), and Trinidad-Tobago; Sapphoa 2 spp. endemic genera of Cuba; Schaueria 15 former endemic to C+E+S Brazil, but 1 sp now intro in Trinidad-Tobago; Sebastiano-schaueria monospecific endemic of SE Brazil; Spathacanthus 3 of 4 Mexico & CAM endemic spp. native to Guatemala, Honduras, and Costa Rica, including 1 narrow endemic of Costa Rica; Stenandrium 50 Americas endemic spp native from S USA to Nicaragua (exc. Belize), plus Bahamas, Turks-Caicos, Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is., and tropical SAM S to C Chile, N Argentina (exc. Guyana, Suriname, French Guiana, N Chile); Stenostephanus 95 Mexico + neoendemic spp. native from Mexico S through CAM (exc. Belize, El Salvador) to Colombia, Venezuela, N+SE Brazil, Ecuador, Peru, and Bolivia; Streblacanthus 3 Mexico & N neoendemic spp. native to Guatemala, Costa Rica, Panama, Peru, and N Brazil; Strobilanthes 1 sp. intro to Belize, El Salvador, Honduras, Nicaragua, Panama, Cuba, Hispaniola, Jamaica, Puerto Rico, Windward Is, Venezuelan Antilles, and Trinidad-Tobago; Suessenguthia 8 N SAM endemic spp. of N Brazil, Peru, and Bolivia; Tessmanniacanthus monospecific endemic Peru?; Tetramerium 9 sub & tropical Americas endemic spp. native to Guatemala, El Salvador, Honduras, Nicaragua, Panama, Venezuela, Colombia, Ecuador, Peru, and Bolivia, including 5 narrow endemics of Peru; Trichanthera 2 neoendemic spp. of Panama, Colombia, Venezuela, N Brazil, Guyana, Suriname, French Guiana, Ecuador, and Peru; Trichosanchezia monospecific endemic Peru; Xantheranthemum monospecific of endemic Peru. Avicennioideae: Avicennia 3 spp. native to CAM, Bahamas, Aruba, Turks and Caicos, Antilles, SW Caribbean, Trinidad-Tobago, Colombia, Venezuela, Guyana, Suriname, French Guiana, N, E, and S Brazil, Uruguay, Ecuador, and Peru. Nelsonioideae: Aymoreana monospecific narrow endemic of E Brazil; Elytraria 11 spp. native to CAM, Cuba, Haiti, Aruba, Trinidad-Tobago, and tropical SAM S to Peru, NW Argentina, C+SE Brazil, and intro to Galapagos and includes 9 narrow endemics of Cuba (6), Haiti, Peru, and Ecuador; Nelsonia 1 sp. intro to El Salvador, Honduras, Nicaragua, Panama, Puerto Rico, Colombia, Ecuador, French Guiana, Bolivia, and N+C+E Brazil; Staurogyne 28-30 spp. native from Nicaragua S to Colombia, Venezuela, Guyana, Suriname, French Guiana, Brazil, Bolivia, and Trinidad and Tobago. Thunbergioideae: Mendoncia ~74 spp. native to CAM (exc. El Salvador), Trinidad-Tobago, and tropical SAM S to Peru, Bolivia, Paraguay, and S Brazil; Thunbergia several spp. intro to Bahamas, Antilles (exc. Cayman Is., Netherlands Antilles), CAM (exc. Nicaragua), and tropical SAM S to N Argentina (exc. French Guiana, N Chile, and Uruguay).

Patagonia Genera Include:

Acanthoideae: Stenandrium 1 sp. native in Bio Bio in C Chile, also in Buenos Aires, Argentina just N of Patagonia.

Additional Information and References

Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, as well as my own personal observations of species in North America.
Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
Delta: Watson, L., and Dallwitz, M.J. (1992+). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
Flora of North America. (1993+). https://floranorthamerica.org/Main_Page.
GBIF.org (2020), GBIF Home Page. Available from: https://www.gbif.org
Naturalista: CONABIO http://www.naturalista.mx (Accessed 2020–current).
Neotropikey: Milliken, W., Klitgård, B., & Baracat, A. eds. (2009+). Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
POWO (2019). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/ Retrieved Winter 2020 – present.
USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; accessed throughout the fall of 2020.
WFO (2022): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

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9 Sep, 2022

How to Identify the Araceae or Arum Family

Arisaema triphyllum flowers in a spadix enclosed in a sheath. Learn to identify the Araceae family with more morphology photos like this. — *Arisaema triphyllum* flowers in a spadix enclosed in a sheath, typical of the Araceae family.
Page Last Updated 2026-05-03

Introduction to the Araceae Family

When you learn how to identify the Araceae family, it’s important to understand that it is part of the Alismatales order of the basal monocot flowering plants. As a monocot, they typically have parallel veins in their leaves. However, as a basal monocot, they diverged early in evolution, so it’s unsurprising that their flowers are not typical at all for a monocot. However, the fact that they are very small and densely packed into a spadix enclosed by a showy spathe is a defining characteristic, making it very easy to recognize in the field.

The Araceae family has always been a favorite of mine, having grown up in the temperate rainforest of the British Columbia coast of western Canada, where skunk cabbage is often found in wet forests and swamps. Most people don’t like the smell, hence the name; however, I love the smell because I love swamps and stinky plants, and when I smell skunk cabbage, odds are there is a swamp for me to explore! I love it so much I even have it tattooed on my back!

Common Botanical Description

If you’re new to plant morphology, this guide is a perfect beginner’s description to learn to identify the Araceae family, with no need to know any scientific jargon. Below is additional information on uses and morphology, as well as pictures to help identify family members and individual species found in North America. But for researchers or those wanting to learn a more in-depth version, check out the Scientific Botanical Description below the images for highly detailed scientific descriptions and genus-level distribution data.

Leaves and Stems: Perennial herbs, shrubs, or vines; some are aquatic plants, and others grow on trees (epiphytes). They usually lack stems and instead frow from underground corms, rhizomes, or above-ground runners. Leaves are arranged spirally or alternately; most have stalks (petioles) and a base that sheaths or wraps around the plant. Leaves may be simple or compound, and they may contain natural holes. They often contain a milky or watery sap.

Flowers: Unique tiny flowers densely packed in a cylindrical structure called a spadix is the most characteristic feature of this family, which makes them easy to identify. The spadix is almost always accompanied by a spathe, which is a large leaf-like bract that may be green or brightly colored and may persist or fall off. The flowers often emit strong, foul odors to attract pollinators.

Reproductive Features: Some species have bisexual flowers with male (stamens) and female (ovary, style, and stigma) parts in the same flower, while others have separate male and female flowers on the same spike (monoecious), usually with males on top and female flowers below. But the flowers are very tiny, and a hand lens would be needed to see any detail.

Fruits: Fruits are usually fleshy berries with one to several seeds. Occasionally the berries merge into a single compound fruit.

Uses of the Araceae

Many Araceae are toxic due to the presence of calcium oxalate crystals, which can irritate the digestive tract when ingested. Despite this, however, many are still important food sources in tropical regions, including Alocasia, Amorphophallus, Colocasia esculenta (taro), Monstera, and Xanthosoma sagittifolium. Some are used as traditional herbal medicines, or their roots are used for fiber or arrow poisons. Many genera are cultivated worldwide as ornamentals both outdoors and indoors as houseplants, including Dieffenbachia, Caladium, Philodendron, Zantedeschia, and many more. The Araceae also have unique plants such as Amorphophallus titanum, which has the most massive inflorescence in all the angiosperms, and Wolffia species, which have the smallest flowers.

Morphology of Araceae in North America

Learn to identify the Araceae family with these morphology photos.

Some Araceae Species I have Covered So Far in North America

Aroideae Subfamily

Arisaema dracontium plant with flower showing an extra-long spadix

Arisaema dracontium—Green Dragon

Herbaceous perennial with one leaf that is compound and divided into two leaflets that are again palmately divided into 5 – 15 leaflets each. Flowers are in a very spadix that sticks out well beyond the sheath, several inches or more. This Araceae member is native to eastern North America, including northeastern Mexico.

Arisamea quinatum plants showing compound leaves with 5 leaflets; compound leaves are relatively common in the Araceae.

Arisaema quinatum or A. triphyllum ssp. quinatum—Southern Jack-in-the-Pulpit

Herbaceous perennial with 3 leaflets per leaf, but the lateral leaflets are deeply 2-lobed, making it look like it has 5 leaflets. Flowers in a spadix enclosed by a fleshy, hooded sheath. Endemic in the southeastern USA, from Texas east to North Carolina.

Arisaema triphyllum flowers in a spadix enclosed in a sheath, typical of the Araceae family.

Arisaema triphyllum – Jack-in-the-Pulpit

Herbaceous perennial with trifoliate compound leaves on long petioles from the ground up. Flowers are in a narrow spadix enclosed by a green or purplish hooded sheathe. Flowers are in a thin green spadix that is closed by a hooded sheath. Native to eastern North America.

Arum italicum—Italian Arum

Herbaceous perennial with large showy sagittate leaves and a large white or yellow spathe that surrounds its white to reddish spadix. Native to the Mediterranean and cultivated in North America.

Calla palustris plants with flowers growing in a wet ditch

Calla palustris—Bog Arum

Aquatic perennial with rounded to cordate leaves 6 – 10 cm long and nearly as wide on a 10 – 20 cm petiole. Flowers in a greenish-yellow spadix and enclosed by a white sheath. Fruit is a cluster of red berries. Native to cool, temperate areas of the Northern Hemisphere. This was in Midland, MI, USA.

Colocasia esculenta invasive plants in Lake Catherine State Park, AR, USA.

Colocasia esculenta—Taro

Herbaceous perennial from an edible corm with large sagittate leaves on long thick petioles. Spreads vegetatively and rarely flowers. Native to tropical eastern Asia but introduced in North America, where it has become invasive. This was in Hot Springs, AR, USA

Peltandra virginica – Green Arrow Arum

Mostly aquatic herbaceous perennials with large sagittate leaves and pale green to white inflorescences enclosed in a darker-colored spathe. Grows in wet, swampy areas. Native throughout eastern North America.

Lemnoideae Subfamily

Lemna minor—Common Duckweed

A tiny floating aquatic plant with two (1-4) small leaves and a single free-floating root. Spreads vegetatively. Flowers are rare and inconspicuous.

Orontioideae Subfamily

Lysichiton americanus plant with spadix and spathe, which are both very typical of the Araceae family.

Lysichiton americanus—Skunk Cabbage

An herbaceous perennial of wet, soggy soils and swampy areas. It has large sessile ovate leaves and a large yellow spathe encasing a rough greenish-yellow spadix. Has a strong skunky odor. This lovely but often misjudged Araceae member is native to northwest North America.

Pothoideae Subfamily

Anthurium andraeanum plant showing spadix and a flattened colorful spathe

Anthurium andraeanum – Painter’s Palette

A tropical perennial plant that is often cultivated as a house plant. It has colorful orange to reddish spathes that do not enclose the yellow spadix. It is native to Colombia & Ecuador.

Scientific Botanical Description of the Arecaceae

Flowers of the Araceae

Plants may be hermaphrodite, monoecious, or rarely dioecious. The inflorescence is characteristic of the family, a terminal cylindrical or ovoid spadix on a peduncle with 3-900 sessile flowers very tightly packed together. When monoecious, the male flowers appear on the upper part of the spadix, with the female flowers below. The spadix is almost always subtended by a persistent or deciduous spathe that is often colored. In the Lemnoideae, the spadix is reduced to 1-4 flowers in a pouch. Flowers are small, sessile, actinomorphic, ebracteate, hypogynous, and often possess a strong odor that most find unpleasant. The perianth is usually only present in bisexual flowers, and no hypanthium is present. When present, the perianth is 2-whorled with 4-9 parts that may be free or basally joined.

Androecium of the Araceae

The androecium has 4, 6, or 8 (1-32) members. Stamens may or may not all be fertile; staminodes are sometimes present. Stamens may be free or connate in Synandria. The arrangement is antitepalous in hermaphrodite flowers that possess a perianth. Anthers are often subsessile, and dehiscence is poricidal, longitudinal, or transverse.

Gynoecium of the Araceae

The gynoecium has one ovary that is 1-3 (to many) locular, may be sessile or embedded in the spadix, and is syncarpous. The ovary is superior with 3(1-50) carpels, usually with as many locules as carpels. There is usually one short style (sometimes absent) with a hemispheric, capitate, or discoid stigma that is sometimes strongly lobed. Placentation is parietal, axile, basal, or apical. Ovules are one to many per carpel and are usually anatropous and bitegmic.

Fruit of the Araceae

The fruits are one- to many-seeded indehiscent berries that may be distinct or, less often, connate in a syncarp. Rarely do the fruits form as dehiscent berries via a stylar plate. Seeds are variable in shape, almost always possess endosperm, are oily and sometimes starchy, and sometimes have a fleshy seed coat.

Habit & Leaf Form of the Araceae

Perennial herbs, shrubs, or vines that may be aquatic or terrestrial, emergent or floating, or epiphytic. They grow from vertical or horizontal rhizomes that may or may not be branched, starchy underground corms, or stolons found at or near the surface. Roots are often mycorrhizal and have no root hairs. They usually do not possess typical stems. Plants typically have calcium oxalate crystals or raphides, milky or watery latex, or rarely colored latex. Leaves may appear before or after the inflorescence, and cataphylls are often seen. Leaves are alternate, bifacial, spiral, distichous, or rarely solitary. A petiole is almost always present, and bases are sheathing with a membranous sheath. The leaf blade is simple or compound and sometimes is perforate or fenestrate. Leaf shape is elliptic to obovate or spatulate and sometimes sagittate–cordate. Venation can be parallel, pinnate-netted, or palmate-netted.

Taxonomy of Araceae

There are approximately 3,667 to 6,500 species in the Araceae family across 143 genera (per APG IV 2026) and currently eight accepted subfamilies, which are undergoing revisions and may change in the future. This family is part of the Alismatales order, which is considered part of the basal monocots, diverging early in monocot evolution:

Aroideae – These have highly variable growth forms, making generalizations difficult. They have staminate flowers with connate stamens with a thick connective. Their pistillate flowers have staminodes. Neither flower type has a perianth. Stigmas, placentation, ovules, etc. are all variable. Their distribution is cosmopolitan.
Gymnostachydoideae – Leaves are two-ranked and linear, margins are minutely toothed, and there is no distinction between the blade and petiole. Their inflorescences are branched. These are restricted to eastern Australia.
Lasioideae – These are often prickly, rooted aquatics. Their petioles are long, warty, aculeate, or brightly colored, and their spathe is often spirally twisted. Their inflorescence flowers basipetally, and they may or may not have a perianth. They have up to 12 stamens, and their anthers have oblique pore-like slits. They are found pantropically.
Lemnoideae – Small floating aquatic herbs with 0-5 unbranched hairless roots. They are made of thalloid stem-leaf units that possess only a primary vein without any vascular tissue. They have no perianth and possess only one stamen and one gynoecium. They have a cosmopolitan distribution.
Monsteroideae – Herbs, climbers, and epiphytes. Their pollen is inaperturate, the style has abundant trichosclereids, ovules 1-4 (-many) per carpel are often basal or sometimes hemianatropous, and there are more than 10 seeds per fruit that are often embedded in mucilage. Distribution is pantropical.
Orontioideae – A variable group that has no vessels, possesses biforine raphides (exc. Lysichiton), leaf blades have a midrib (exc Orontium), have flowers with usually inferior ovaries (exc. Orontium), may or may not have styles. Their ovules are either hemianatropous or basal. Distribution is north temperate.
Pothoideae – The spathe does not enclose the spadix, may be erect to reflexed, and is persistent in the fruit. Placentation of ovules is basal or parietal. Distribution is pantropical, excluding Africa.
Zamioculcadoideae – Rhizomatous plants with leaves that are usually 1-3-compound or simple in Stylochaeton. Leaf fine venation is reticulate, and the leaves are pulvinate along the petiole or petiolules. They have staminate and pistillate flowers. Placentation of ovules is axile, and there is one ascending ovule per carpel. Distribution is restricted to Africa.

Genera of the Arecaceae:

Aroideae: Adelonema (16), Aglaodorum (1), Aglaonema (26), Alocasia (91), Ambrosina (1), Amorphophallus (246), Anchomanes (6), Anubias (8), Apoballis (14), Aridarum (5), Ariopsis (3), Arisaema (224), Arisarum (3), Arophyton (7), Arum (26), Asterostigma (8), Bakoa (1), Bidayuha (1), Boakoaella (?), Biarum (24), Bognera (1), Boycea (1), Bucephalandra (32), Burttianthus (9), Caladium (19), Calla (1), Callopsis (1), Carlephyton (4?), Cercestis (11), Chlorospatha (70), Colletogyne (1), Colobogynium (1), Colocasia (15), Cryptocoryne (78), Culcasia (27), Dieffenbachia (60), Dracunculus (2), Eminium (8), Fenestratarum (2), Filarum (1), Furtadoa (?), Galantharum (1), Gamogyne (6), Gearum (1), Gorgonidium (8), Gosong (1), Hapaline (9), Hayarum (1), Helicodiceros (1), Hera (1), Hestia (1?), Heteroaridarum (3), Homalomena (177), Hottarum (1), Idimanthus (1), Incarum (1 Not listed in APG), Jasarum (1), Josefia (1), Kiewia (3), Lagenandra (24), Lazarum (16), Leucocasia (1), Lorenzia (1), Mangonia (2), Montrichardia (2), Nabalu (1), Naiadia (1), Nephthytis (5), Ooia (12), Peltandra (2), Philodendron (626), Philonotion (3 or syn. of Schismatoglottis), Phymatarum (1), Pichinia (1), Pinellia (11), Piptospatha (3), Pistia (1), Protarum (1), Pseudodracontium (?), Pseudohydrosme (3), Purseglovia (?), Remusatia (4), Rhynchopyle (7), Sauromatum (11), Scaphispatha (2), Schismatoglottis (97), Schottariella (1), Schottarum (3), Spathantheum (1), Spathicarpa (3), Steudnera (11), Synandrospadix (1), Syngonium (41), Taccarum (6), Tawaia (1), Theriophonum (6), Toga (6), Typhonium (79), Typhonodorum (1), Ulearum (2), Vesta (1), Vietnamocasia (1), Xanthosoma (199), Zantedeschia (8), Zomicarpa (2), Zomicarpella (2).

Gymnostachydoideae: Gymnostachys (1).

Lasioideae: Dracontioides (2) and Dracontium (30).

Lemnoideae: Anaphyllopsis (3), Anaphyllum (2), Cyrtosperma (15), Landoltia (?), Lasia (2), Lasimorpha (1), Lemna (13), Podolasia (1), Pycnospatha (2), Spirodela (4), Urospatha (13), Wolffia (11), and Wolffiella (10).

Monsteroideae: Alloschemone (2), Amydrium (5), Anadendrum (15), Epipremnum (15), Heteropsis (19), Monstera (73), Rhaphidophora (105), Rhodospatha (45), Scindapsus (36), Spathiphyllum (76 inc. Holochlamys), and Stenospermation (58).

Orontioideae: Lysichiton (2), Orontium (1), and Symplocarpus (6).

Pothoideae: Anthurium (1459), Pothoidium (1), and Pothos (66).

Zamioculcadoideae: Gonatopus (5), Stylochaeton (22 s/t as Stylochiton), and Zamioculcas (1).

Key Differences From Similar Families

The Araceae are easily differentiated from similar families with their spadix of numerous small flowers with their unique subtending spathes, their leaves with either parallel or netted venation (unlike only parallel in most monocots), their raphide crystals, and their seeds with endosperm.

Distribution of Araceae

The Araceae are most diverse in the neotropics of the Americas but are also found in the Old World tropics and temperate regions.

Distribution of Araceae in the Americas

Canadian Genera Include:

Aroideae: Arisaema 2 spp. native to MB, ON, QC, NB, NS, and PE; Arum 1 sp. intro to BC; Calla 1 pan-north temperate sp native to all of Canada except NT; Peltandra 1 E NAM (+Cuba) endemic sp. native to ON and QC; Pinellia 1 sp. ephemeral intro ON; Pistia 1 pantropical sp. intro to ON. Lemnoideae: Lemna 6 of 18 cosmopolitan spp. native to all of Canada except NF, where it was introduced; Spirodela 1 cosmopolitan sp. native to BC, AB, SK, MB, ON, QC, NB, NS, and PE; Wolffia 4 cosmopolitan spp., including 3 native to BC, AB, SK, MB, ON, QC, and NB and 1 intro in ON. Orontioideae: Lysichiton 1 sp. native to BC; Symplocarpus 1 E NAM endemic sp. native to ON, QC, NB, and NS.

USA Genera Include:

Aroideae: Aglaonema 1 sp. intro to FL; Alocasia 1 sp. intro to FL, TX, and HI; Arisaema 2 spp. native to the E USA from ND S to TX and all states E of that; Arum 2 spp. intro to WA, OR, CA, MO, IL, VI, and SC; Caladium 1 sp. intro to LA and FL; Calla 1 pan-north temperate sp native ND, MN, IA, WI, IL, IN, MI, OH, PA, MD, NJ, NY, CT, RI, MA, VT, NH, and ME; Colocasia 1 sp. intro to TX, LA, MS, AL, GA, FL, SC, NC, PA, and HI; Cryptocoryne 1 sp. intro to TX and FL; Dracunculus 1 sp. intro to OR, CA, and TN; Epipremnum 1 sp. intro to FL, HI, Virgin Is., and Puerto Rico; Peltandra 2 E NAM (+Cuba) spp. native KS S to TX plus E USA from MN S to LA and all states east, including 1 endemic to SE USA, also intro in OR and CA; Philodendron 1 sp. intro to FL and HI; Pinellia 1 sp. intro to CA, OH, WV, MD, NJ, PA, NY, and CT; Pistia monospecific pantropical sp. native to CA, AZ, CO, KA, TX, MO, LA, MS, GA, FL, SC, NC, OH, MD, DE, NY, NJ, and CT; Syngonium 1 sp. intro to FL; Xanthosoma 2 spp. intro to TX, FL, and HI; Zantedeschia 2 spp. intro to CA, OR, PA, and HI. Lemnoideae: Lemna 9 spp. native throughout the entire USA, including AK and HI; Spirodela 2 cosmopolitan spp. native throughout the entire continental USA and HI; Wolffia 7 cosmopolitan spp. native to most of the USA except NV, AZ, NM, and CO; Wolffiella 5 cosmopolitan spp. native to WA, CA, TX, OK, MO, AR, LA, IL, IN, OH, KY, TN, MS, AL, GA, FL, SC, NC, VA, PA, NJ, and MA. Monsteroideae: Epipremnum 1 sp. intro to FL and HI. Orontioideae: Lysichiton 1 sp. native to AK, WA, OR, CA, ID, MT, and WY; Orontium monospecific SE USA endemic sp. native from TX E to FL, N to KY, MA, and RI; Symplocarpus 1 E NAM endemic sp. native to MN, IA, WI, IL, IN, OH, KY, TN, NC, VI, WV, MI, PA, MD, DE, NJ, NY, CT, RI, MA, VT, NH, and ME.

Mexico Genera Include:

Aroideae: Aglaonema 1 sp. intro to NL, Sin, Jal, Son, Ver, Gro, Chi, Tab, and Cam; Alocasia 5 spp. intro from Sin E to Coa and all S Mexico; Arisaema 5 spp. native and including 1 intro in Sin, NL, Nay, Tam, SLP, Jal, Col, Mic, Mex, Pue, Gro, Ver, Oax, and Chi; Arum 1 sp. intro to NL, Jal, and Mex; Dieffenbachia 2 spp. native from Sin to S NL and all through S Mexico; Dracunculus 1 sp. intro to Chi, Cam; Leucocasia 1 sp. intro to Jal and Pue; Peltandra 1 sp. intro Tlx; Philodendron ~44-46 spp. native and some intro throughout all of Mexico; Pinellia 1 sp. intro Mex; Pistia monospecific pantropical sp. native throughout Mexico; Syngonium 9 neo spp. native BCS, Sin E to NL, and all through S Mexico; Typhonium 1 sp. intro to Oax, Pue, Ver, Chi, and SLP; Xanthosoma 8 neotropical spp. native most of Mexico exccept north-central and northeast; Zantedeschia 1 sp. intro to Mex. Lasioideae: Dracontium 1 sp. a narrow endemic of SW Chi. Lemnoideae: Lemna 7 spp. native throughout all of Mexico; Spirodela # sp. native throughout all of Mexico; Wolffia 2 cosmopolitan spp. native in Jal, Nay, Gto, Chi, Mex, Qro, Mor, and Cd Mex; Wolffiella 4 cosmopolitan spp. native to NE+C+SE Mexico. Monsteroideae: Monstera 13 neoendemic spp. native Sin E to NL and all through S Mexico, but primarily in the tropical south; Rhodospatha 1 neo sp. native to Ver and Chi; Spathiphyllum 5 spp. including 4 native and 1 intro to Nay E to Ver and all of S Mexico, including 1 endemic to SE Mexico. Pothoideae: Anthurium 31 spp. native (and 1 intro) from Sin to S NL and throughout S Mexico. Zamioculcadoideae: Zamioculcas 1 sp. intro QR.

Neotropical Genera Include:

Aroideae: Adelonema 16 neoendemic spp. native to Costa Rica, Panama, Colombia, Peru, Bolivia, N Brazil, French Guiana, Guyana, and Suriname; Aglaonema 1 sp. intro to Cuba, Puerto Rico, Trinidad-Tobago, and Venezuelan Antilles; Alocasia 5 spp. intro to Cuba, Hispaniola, Jamaica, Puerto Rico, Leeward & Windward Is., Trinidad-Tobago, Venezuelan Antilles, NE Brazil, Venezuela, Paraguay, and Galapagos; Amorphophallus 1 sp. intro Trinidad-Tobago; Arum 1 sp. intro to NE Argentina; Asterostigma 8 W SAM endemic spp. native to most of brazil and in NE Argentina; Bognera monospecific endemic to N Brazil; Caladium 19 neoendemic spp. native from Honduras S to Peru, NW Argentina, Brazil, and to Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is., Venezuelan Antilles, and Trinidad-Tobago; Chlorospatha 70 neoendemic spp. native to Costa Rica, Panama, Colombia, and Ecuador; Colocasia 2 spp. introduced to Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is, Trinidad-Tobago, Venezuelan Antilles, Galapagos, Honduras, Nicaragua, Costa Rica, Colombia, Venezuela, Guyana, Brazil, Ecuador, Peru, Bolivia, and Paraguay; Dieffenbachia 60 neoendemic spp. native from S Mexico S through to Peru, Bolivia, NE Argentina (except Uruguay), and including all of the West Indies; Epipremnum 1 sp. intro to Bermuda, Honduras, Costa Rica, Colombia, Ecuador, Suriname, Trinidad-Tobago, Venezuelan Antilles, and Leeward and Windward Is.; Filarum monospecific endemic to Peru; Gearum monospecific endemic to N+C Brazil; Gorgonidium 8 SAM endemic spp. native to Peru, Bolivia, and N Argentina; Idimanthus monospecific narrow endemic to SE Brazil; Incarum 1 W SAM endemic sp. native to Ecuador, Peru, and Bolivia (NOT listed in APG); Jasarum 1 N SAM endemic sp. native to Venezuela and Guyana; Lorenzia monospecific endemic to N Brazil; Mangonia 2 E SAM endemic spp. native to S Brazil and Uruguay; Montrichardia 2 neoendemic spp. native to Guatemala, Belize, Honduras, Nicaragua S to Peru, Bolivia, N+SE Brazil, Trinidad-Tobago, and the Leeward & Windward Is.; Peltandra 1 E NAM sp. native to Cuba; Philodendron ~600 neoendemic spp. native throughout CAM, the West Indies, and N SAM S to Bolivia, NE Argentina, and S Brazil (excluding Uruguay); Philonotion 3 N SAM endemic spp. native to Colombia, Venezuela, Guyana, French Guiana, Suriname, N Brazil, Peru, and Bolivia (listed as syn. of Schismatoglottis in APG??); Pistia monospecific pantropical sp. native throughout CAM, the West Indies, and SAM S to Peru, Bolivia, and NE Argentina; Scaphispatha 2 N SAM endemic spp. native to most of Brazil and Bolivia; Spathantheum monospecific W. SAM endemic sp. of Peru, Bolivia, and NW Argentina; Spathicarpa 3 E SAM endemic spp. native to Brazil, Bolivia, Paraguay, NE Argentina, and Uruguay; Synandrospadix monospecific endemic to Peru, Bolivia, Paraguay, and NW Argentina; Syngonium 41 Mexico + neoendemic spp. native from Mexico S to Peru, Bolivia, C+SE Brazil, Greater Antilles, Trinidad-Tobago, Venezuelan Antilles, and intro S Brazil, Bahamas, Netherland Antilles, Leeward & Windward Is.; Taccarum 6 SAM endemic spp. of Peru, Brazil, Paraguay, Bolivia, and NE Argentina; Typhonium 1 sp. intro to NE+S Brazil, Cuba, Trinidad-Tobago, and Windward Is.; Ulearum 2 N SAM endemic spp. of N Brazil, Ecuador, and Peru; Xanthosoma ~140 spp. native from Mexico S through to Peru, NW Argentina, Paraguay, S Brazil (exc El Salvador), plus Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is., Trinidad-Tobago, and is intro to Galapagos, Jamaica, Venezuelan Antilles, and Cayman Is.; Zantedeschia 1 sp. intro to Nicaragua, Costa Rica, Colombia, Ecuador, NE Brazil, Dominican Republic, Puerto Rico, and Trinidad-Tobago; Zomicarpa 2 narrow endemic spp. of NE Brazil; Zomicarpella 2 N SAM endemic spp. of Colombia, N Brazil, and Peru. Lasioideae: Dracontioides 2 spp. endemic to NE+SE Brazil; Dracontium 29 neoendemic spp. native to the Dominican Republic, Puerto Rico, Trinidad-Tobago, Windward Is., and from Nicaragua S to Peru, Bolivia, Paraguay, and C+SE Brazil. Lemnoideae: Anaphyllopsis 3 N SAM endemic spp. native Venezuela, French Guiana, Suriname, and N Brazil; Lemna 4 spp. native throughout the entire Neotropical zone S to C Chile, Argentina; Spirodela 3 spp. including 2 native and 1 intro throughout all of Neo zone except Guyana, French Guiana, Galapagos, and N Chile; Urospatha 13 neoendemic spp. native to Guatemala, Honduras, Nicaragua S to Peru, Bolivia, Paraguay, and C+SE Brazil; Wolffia 5 cosmopolitan spp., including 3 native (includes 1 endemic to Colombia) and 2 intro found in Guatemala, El Salvador, Honduras, Greater & Lesser Antilles (except Venezuelan Antilles), Colombia, Ecuador, Venezuela, Suriname, Brazil, Bolivia, Paraguay, Uruguay, C Chile, and NE+NW Argentina; Wolffiella 5 cosmopolitan spp. native to Guatemala, El Salvador, Honduras, Costa Rica S to C Chile, N Argentina (exc N Chile), plus Greater Antilles, Leeward & Windward Is, and Trinidad-Tobago. Monsteroideae: Alloschemone 2 N SAM endemic spp. native to N Brazil and Bolivia; Epipremnum 1 sp. intro to Bermuda, Cuba, Hispaniola, Puerto Rico, Trinidad-Tobago, Leeward & Windward Is., Venezuelan Antilles, Colombia, Ecuador, Suriname, and E Brazil; Heteropsis 19 neoendemic spp. native from Nicaragua S to Peru, Bolivia, N Brazil, plus NE+S+SE Brazil; Monstera 73 former neoendemic spp. native from S Mexico S through to Peru, Bolivia, C+S Brazil, Leeward & Windward Is., Netherlands Antilles, and intro to Puerto Rico; Rhodospatha 45 neoendemic spp. native from S Mexico S through CAM (except El Salvador) and N SAM to Peru, Bolivia, N+SE Brazil, and Trinidad-Tobago; Spathiphyllum ~60 spp. native from S Mexico S through CAM and N SAM to Peru, N+C+SE Brazil, Trinidad-Tobago, and intro to Cuba, Puerto Rico, Dominican Republic, and Venezuelan Antilles; Stenospermation 58 neoendemic spp. native to Guatemala, Honduras, and Nicaragua S to Peru, Bolivia, N Brazil, plus disjunct in SE Brazil. Pothoideae: Anthurium 1459 neoendemic spp. native from Mexico all the way south through to Peru, Bolivia, and NE Argentina (except Uruguay) plus all throughout the West Indies (excluding the Bahamas).

Patagonia Genera Include:

Lemnoideae: Lemna 1 sp. native to SE Argentina; Spirodela 1 cosmopolitan sp. native to SE Argentina and C. Chile; Wolffiella 1 cosmopolitan sp. native to SE Argentina.

Additional Information and References

Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, but also a lot comes from my own observations of North American species.
Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
Flora of North America (FNA) (1993+). https://floranorthamerica.org/Main_Page.
Delta: Watson, L., and Dallwitz, M.J. (1992+). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
GBIF.org (2020), GBIF Home Page. Available from: https://www.gbif.org
Naturalista: CONABIO http://www.naturalista.mx (Accessed 2020–current).
Neotropikey: Milliken, W., Klitgård, B., & Baracat, A. eds. (2009 onwards). Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
POWO (2019). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/ Retrieved Winter 2020 – present.
USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; accessed throughout fall of 2020.
WFO (2022): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

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7 Sep, 2022

How to Identify the Araliaceae / Ginseng Family

Oplopanax horridus Devil's Club plant with flowers. Learn to identify the Araliaceae family. — *Oplopanax horridus* – Devil’s Club plant with flowers
Page Last Updated May 14, 2026

Introduction to the Araliaceae Family

The Araliaceae family is best known for its most popular plant, ginseng. But there are so many other lovely plants in this family. My personal favorite member of this family is Oplopanax horridus, or Devil’s Club. It’s pretty typical of the family growing as a shrub with large leaves and small flowers in tall umbels followed by small red drupes.

The Araliaceae are part of the Apiales order of core dicots and are very closely related to the Apiaceae (carrot) family and have many overlapping characteristics. In general, however, the Apiaceae are usually herbs that produce dry schizocarps, while the Araliaceae are usually shrubs or trees and usually produce berry-like drupes.

Common Botanical Description

If you’re new to plant morphology, this guide is a perfect beginner’s description to learn to identify the Araliaceae family, with no need to know any scientific jargon. Below this section are morphology photos to help you identify the family, followed by pictures of individual species found in North America. But for researchers or those wanting to learn a more in-depth version, refer to the Scientific Botanical Description below the images for highly detailed scientific descriptions and genus-level distribution data.

Leaves and Stems: This family is mostly perennial trees and shrubs, but there is an occasional woody vine and herb as well. None release milky juices when damaged. Most have medium to large leaves, including ones over 3 m long. Leaves are usually arranged in a spiral pattern around the stem and have sheaths that wrap around their base. Leaf blades are simple or compound (made of leaflets); when simple, the margins are often divided in some way, often lobed and maple leaf-like.

Flowers: The flowers are usually individually small but arranged in spikes or heads, sometimes branched, and occasionally in umbels similar to the Apiaceae family, which can cause confusion. The flowers are symmetrical with five petals that are often thick or fleshy with a highly variable calyx that may be reduced to a rim of teeth.

Reproductive Features: This varies in the family from bisexual flowers with both male (stamens) and female (ovary, style, stigma) parts in the same flower to separate male and female flowers on separate plants (dioecious). There are usually 5 stamens, but up to 100 in some species. Flowers usually have a fleshy nectar-producing disk at the base of the styles (tubes that capture pollen).

Fruits: Fruits are mostly fleshy berries or drupes (fleshy fruits with stony pits, like a cherry). But sometimes it is a dry fruit that spits into segments (schizocarp) similar to the Apiaceae (carrot) family.

Uses of Araliaceae

Ornamentals include the angelica tree (Aralia spinosa) and ivy (Hedera spp.), as well as houseplants such as Hedera, Aralia, Polyscias, Schefflera, and Fatsia. Note that Hedera species have become a widespread invasive species in many areas and should only be grown with extreme caution. Chinese rice paper comes from the pith of Tetrapanax papyriferus.

Medicinal herbs include ginseng roots from Panax quinquefolius and devil’s club (Oplopanax horridus) root bark used for respiratory conditions.

Morphology of Araliaceae in North America

Learn how to identify the Araliaceae family with these morphology photos of the Araliaceae family. — Morphology of the Araliaceae Family

Some Araliaceae Species in North America

Aralioideae Subfamily

Aralia nudicaulis plant before flowering, showing compound leaves common in the Araliaceae family.

Aralia nudicaulis – Wild Sarsaparilla

Herbaceous perennial from underground stems. Large compound leaves have 5 (3 – 7) finely serrated leaflets, often purplish green. Small white flowers in rounded clusters 4 – 5 cm wide on scapes not much taller than the leaves. Flowers are followed by edible purple-black berries. Native to northern and eastern North America.

Aralia spinosa deciduous shrub getting its new spring leaves

Aralia spinosa – Devil’s Walking Stick

Aromatic spiny deciduous shrub or small tree 2 – 8 m tall with exceptionally large bipinnate leaves 70 – 120 cm long. Small white flowers in compound panicles are followed by purplish-black berries. Native to eastern North America.

Fatsia japonica plant with berry-like drupes (fruits), the most common fruit of the Araliaceae family.

Fatsia japonica – Paperplant

Evergreen shrub with stout, sparsely branched stems. Large 20 – 40 cm deeply palmately lobed leaves have 7 – 9 lobes, are spirally arranged, are leathery, and are on long petioles. Flowers are small, white, born in dense terminal compound umbels, followed by small black berries. Native to Japan and Korea, cultivated in North America.

Hedera helix - invasive English Ivy growing on a native tree; vines are uncommon in the Araliaceae family.

Hedera helix – English Ivy

A highly invasive, vigorous root-climbing vine with variably 3-5 lobed leaves, depending on the cultivar and if it has reached reproductive age. It seldom flowers but produces small umbels of greenish-yellow flowers followed by purple-black berries. It spreads mostly vegetatively and takes over entire areas when it is left unchecked. Click for more information!

Oplopanax horridus – Devil’s Club

Woody deciduous spiny perennial shrub with large spiny palmately lobed leaves, small yellow-green flowers in racemes followed by clusters of small red berry-like drupes. Endemic to North America, mostly the Pacific Northwest, with a small disjunct population in the Great Lakes. Click the link for more info!

Hydrocotyloideae Subfamily

Hydrocotyle ranunculoides plants in a Louisiana bayou lake; aquatics are rare in the Araliaceae family

Hydrocotyle ranunculoides – Floating Pennywort

A creeping, mat-forming aquatic perennial of slow-moving, shallow water or wet mud. It has thin stems that may be above or below the water and rounded to kidney-shaped leaves with about 3-7 shallow lobes on the margins and a deeply notched base that makes it appear almost peltate. Small flowers appear separately in clusters. Native to North, Central, & South America but has become invasive in other parts of the world.

Scientific Botanical Description of the Araliaceae Family

Habit & Leaf Form of the Araliaceae

The Araliaceae are a family of shrubs, moderate-sized trees (occasionally very large in some Polyscias), woody epiphytes, vines, and occasionally herbs (Panax, some Aralia, and the Hydrocotyloideae); occasionally some are switch plants. They are self-supporting, epiphytic, or climbing; when climbing, they may be stem twiners or root climbers. Almost always pachycaul with large leaves and thick stems, but sometimes they are leptocaul in Pseudopanax, where long and short shoots are seen. They are non-laticiferous without colored juice, with or without essential oils, and resinous.

Plants may or may not be conspicuously heterophyllous (sometimes, e.g., Hedera helix). Leaves are usually medium-sized but can be enormous (over 3 m in Aralia) or rarely small (1–2 cm in Pseudopanax anomalum). Their attachment to the stem is nearly always alternate, mostly spiral, or rarely distichous, four-ranked, opposite (Cheirodendron, Polyscias), or whorled (Panax). Leaves are often leathery, usually petiolate, but sometimes subsessile. They are usually more or less sheathing but may sometimes be non-sheathing; when sheathing, they have free margins. Leaves may be gland-dotted or not, and they may be aromatic or odorless. Leaf shapes are mostly simple or sometimes compound, including ternate, pinnate, palmate, multiply compound, and sometimes peltate (as in Hydrocotyloideae and some Harmsiopanax). When simple, the lamina is usually dissected pinnatifid or palmatifid but may be entire. They are pinnately or palmately veined. Leaves may or may not have stipules; when present, they are intrapetiolar, often adnate to and hard to distinguish from the petiole base. Some taxa have spines (as in Oplopanax).

Flowers of the Araliaceae

Plants may be hermaphroditic, monoecious, andromonoecious, gynomonoecious, dioecious, or polygamomonoecious. Flowers are aggregated in spikes, heads, and sometimes umbels (comparable to the Apiaceae) and sometimes in large compound inflorescences. Inflorescences are terminal, axillary, leaf-opposed, or rarely epiphyllous. Flowers are usually more or less 5-merous and cyclic and rarely calyptrate. The floral receptacle has neither an androphore nor a gynophore. Perianth has a distinct calyx and corolla or may be petaline, has 10(6–24) parts, and is usually two-whorled and isomerous or anisomerous, but in Meryta, the flower is whorled.

Calyx, when present, has 3–5 (–12) parts; is one whorled, free or connate, entire, lobulate, blunt-lobed, or toothed (when sometimes reduced to small teeth or a rim); and is often open when in bud. Corolla has 5 (3–13) parts where partially divided or lobed segments sometimes complicate the interpretation of parts. It is one whorled and usually alternates with the calyx, with most genera having five sepals alternating with five petals (exceptions do occur). The corolla is free or partially connate at the base, is rarely calyptrate, may be valvate or imbricate (in Aralieae), is always regular, and is often fleshy. Petals are usually sessile, often with broad bases inserted around the whole circumference of the upper part of the ovary.

Androecium of the Araliaceae

The androecium has 5 (3–12) or 10–100 members made of exclusively fertile stamens that are free of the perianth and one another and all of equal size. Stamens are usually isomerous with the perianth, are inflexed in bud, with filaments and have usually short and fleshy anthers. Stamens may alternate with the corolla members (usually when equal in number), or they may be opposite to them. Anthers are dorsifixed, dehisce via longitudinal slits, and introrse. Anthers are almost always tetrasporangiate (but occasionally appear bisporangiate by fusion during development) or multisporangiate in some Plerandra.

Gynoecium of the Araliaceae

The gynoecium is 2–5(1–100) carpelled, and the pistil is 2–5(1–100) celled. The gynoecium is synovarious to syncarpous with the styles almost always forming a solid or sometimes hollow stylopodium. Or rarely, the gynoecium can appear monomerous in some Polyscias. It may be partly or fully inferior, or rarely superior (sometimes in Tetraplasandra). The ovary is 1–100 locular, and locules have no false septa. The epigynous disk is present with a nectariferous disk between the stylopodium and stamens. The number of styles varies widely from 1–100. When there are two or more, then they are free or partially joined and apical. Stigmas are usually present as a double-stigmatic crest capping the stylopodium and are wet or dry type, papillate, and of Group II and III types. Placentation, when bi/plurilocular (almost always), is axile to apical. When unilocular (rarely) parietal to apical. Ovules in the single cavity (1–2, if two, the second is typically abortive) per locule, pendulous, epitropous, with ventral raphe, anatropous, unitegmic, and usually crassinucellate or otherwise tenuinucellate.

Fruit of the Araliaceae

Fruit may be fleshy or non-fleshy, often an indehiscent berry or drupe (most Aralioideae) with separable pyrenes or with one stone (there are as many pyrenes as locules). Sometimes it will be a schizocarp with 2-5(6-100) mericarps (mostly Hydrocotyloideae). Gynoecia may combine to form multiple fruits. Seeds are endospermic and oily and may be ruminate (e.g., Hedera).

Taxonomy of Araliaceae

There are 1450 species in 43 genera within the Apiales order of core Eudicots (dicots). Currently, there are two recognized subfamilies in the Araliaceae.

Aralioideae – The largest subfamily is made mostly of shrubs and trees, sometimes herbs or root or stem climbers. Leaves are usually pinnately to palmately compound, stipulate with connate, intrapetiolar, hooded, or sometimes cauline stipules. Fruit is almost always a drupe.
Hydrocotyloideae – Herbaceous perennials, sometimes annuals, and some aquatics, but are often found near bodies of water. The stem has endodermis; it is often prostrate, creeping, or mat-forming. The leaf lamina is orbicular–peltate or deeply twice-lobed palmately; the margin is crenate or serrate, and they are stipulate (cauline or petiolar). Flowers are small, and sepals are often tiny or absent.

The Hydrocotyloideae historically was considered part of the Apiaceae. However, modern phylogenetics showed that it was polyphyletic in the Apiaceae and was moved to the Araliaceae instead. Also, there have been a lot of generic changes, with some genera increasing massively, others decreasing, some appearing, and some disappearing, so while this is as up-to-date (May 2026) as the information I have, the family composition is likely to change some in the near future.

Genera:

Aralioideae: Anakasia (1), Aralia (73), Arthrophyllum (2 = Phylloctenium?), Astropanax (15), Astrotricha (20), Brassaiopsis (45), Cephalaralia (1), Cheirodendron (6), Crepinella (33), Cuphocarpus (5?), Cussonia (20), Dendropanax (97), Didymopanax (38), Eleutherococcus (29), Fatsia (3), Gamblea (4), Gastonia (??), Harmsiopanax (3), Hedera (19), Heptapleurum (322), Heteropanax (9), Hunaniopanax (1-2?), Kalopanax? (1), Macropanax (18), Megalopanax? (?), Merrilliopanax (3), Meryta (28), Motherwellia (1), Munroidendron (?), Neocussonia (16), Oplopanax (3?), Opopanax (4), Oreopanax (148), Osmoxylon (61), Panax (15), Pentapanax (?), Plerandra (33), Polyscias (181), Pseudopanax (7), Raukaua (6), Schefflera (13), Sciodaphyllum (146), Seemannaralia (1), Sinopanax (1), Tetrapanax (1), Tetraplasandra (? or syn. of Polyscias), Trevesia (8), Woodburnia (1).

Hydrocotyloideae: Hydrocotyle (182), Trachymene (59).

Key Differences From Similar Families

The Araliaceae and Apiaceae are both similar to and closely related to each other, and often the two can be hard to differentiate. However, some more common differences include the fact that the Apiaceae are usually herbs vs. usually shrubs and trees in the Araliaceae and leaves that usually lack stipules in the Apiaceae vs. those that are usually present in the Araliaceae. Also, the fruit in Apiaceae is usually a dry schizocarp with two mericarps vs. usually a berry-like drupe in the Araliaceae (but sometimes a schizocarp).

Distribution of Araliaceae

Araliaceae is mostly a tropical family, but some are endemic to temperate climates as well. They are in Eurasia, Africa, Australia, New Zealand, New Caledonia, the Pacific Islands, and the Americas, from Arctic Canada to temperate South America.

Distribution of Araliaceae in the Americas

Canadian Genera Include:

Aralioideae: Aralia 5 spp. native to all of Canada except NU; Eleutherococcus 1 sp. intro to ON; Hedera 1-2 spp. intro BC and ON, very invasive in coastal BC; Kalopanax 1 sp. intro to ON; Oplopanax 1 sp. native to BC, AB, YT, and ON; Panax 2 spp. native to ON, QC, NB, NS, and PE. Hydrocotyloideae: Hydrocotyle 4 native to ON, QC, NB, NS, PE, and NL (excluding Labrador) and intro to BC.

USA Genera Include:

Aralia 8 spp. are native and intro to all of the USA exccept NV; Cheirodendron 5 of 6 C Pacific endemic spp. endemic to HI; Eleutherococcus 1 sp. intro to UT, IN, KY, OH, WV, PA, NY, CT, and MA; Hedera 3 spp intro and invasive to most of the USA except NV, MT S to NM, ND S to OK, MN, IA, WI, VT, NH, ME, and inc. HI; Heptapleurum ? spp. intro FL and HI; Kalopanax 1 sp. intro to NY, CT, MD, VA, OH, and IN; Oplopanax 1 sp. native to WA, OR, ID, WY, MI, NY, and AK; Panax 2 spp. native to all E USA from ND S to TX and all E except ND, TX, and FL; Polyscias 10 spp including 9 spp. native/endemic to HI and 1 sp. intro in FL; Tetrapanax monospecific intro AL, FL, and HI. Hydrocotyloideae: Hydrocotyle 9 spp. native and intro to most of the USA except ID, MT, WY, CO, ND, SD, NE, and IA and it is intro in HI.

Mexico Genera Include:

Aralioideae: Aralia ~5-9 spp. native throughout all of Mexico; Dendropanax ~3-6 spp. native to most of Mexico except BC, BCS, Son, and Sin; Didymopanax 1 sp. native to SW+SE Mexico, Ver; Oreopanax 13? Mexico + neoendemic spp. native throughout all of Mexico, including the Mexican Pacific Is. Hydrocotyloideae: Hydrocotyle 5-10 spp. native throughout all of Mexico.

Neotropical Genera Include:

Aralioideae: Aralia ~ 8 spp. native to CAM, Cuba, Hispaniola, Colombia, Venezuela, Peru, Bolivia, Paraguay, N Argentina, E+S Brazil; Crepinella 33 NW SAM endemic spp. of Colombia, Venezuela, Guyana, N+C Brazil, Ecuador, and Peru; Dendropanax ~75 spp. native to CAM, Greater Antilles, Leeward Is, Venezuelan Antilles, Trinidad-Tobago, tropical SAM S to Peru, Bolivia, NE Argentina (except for Suriname, French Guiana, and Uruguay); Didymopanax 38 Mexico & neoendemic spp. native to CAM, Cuba, Hispaniola, Puerto Rico, Leeward Is, Trinidad-Tobago, tropical SAM S to NE Argentina (exc NW Argentina, N Chile), including at least 12 narrow endemics of Brazil; Fatsia 1 sp. intro Juan Fernandez Is; Heptapleurum 1? sp. intro to Bermuda, Bahamas, Hispaniola, Jamaica, Puerto Rico, Leeward & Windward Is; Oreopanax 148 Mexico + neoendemic spp. of CAM, Antilles (exc Cayman Is, Aruba, Netherlands Antilles), Trinidad-Tobago, Colombia, Venezuela, Guyana, Suriname?, French Guiana, N+E+S Brazil, Ecuador, Peru, Bolivia, NW Argentina; Plerandra 1 sp. intro to Trinidad-Tobago; Polyscias ? spp. intro to El Salvador, Bahamas, Hispaniola, Leeward Is., Puerto Rico, Trinidad-Tobago, and Venezuelan Antilles; Raukaua 1 sp. endemic to N+C Chile; Sciodaphyllum 146 neoendemic spp. of Jamaica, Nicaragua, Costa Rica, Panama, Colombia, Ecuador, Peru, Bolivia, and Venezuela; Tetrapanax monospecific intro to S Brazil. Hydrocotyloideae: Hydrocotyle ?? spp. native and widespread in moist habitats of CAM, Bermuda, the Bahamas, Cuba, Hispaniola, Jamaica, Puerto Rico, the Leeward & Windward Is., Galapagos, and all of SAM, with high diversity in the Andes.

Patagonia Genera Include:

Aralioideae: Raukaua 2 spp. endemic to N+C Chile (1) + S Argentina (1). Hydrocotyloideae: Hydrocotyle ? spp. native throughout Patagonia and the Falkland Is.

Additional Information and References

Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, as well as my own personal observations of plants in North America.
Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
Delta: Watson, L., and Dallwitz, M.J. (1992+). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
GBIF.org (2020), GBIF Home Page. Available from: https://www.gbif.org
Naturalista: CONABIO http://www.naturalista.mx (Accessed 2020–current).
Neotropikey: Milliken, W., Klitgård, B., & Baracat, A. eds. (2009 onwards). Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
POWO (2019). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/ Retrieved Winter 2020–current.
USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; accessed throughout fall of 2020.
WFO (2022): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

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7 Sep, 2022

5 Sep, 2022

Plant Families of North America

Alismatales Order – Monocot Clade
Apiales Order – Eudicot Clade
Caryophyllales Order – Eudicot Clade
Gentianales Order – Eudicot Clade
Lamiales Order – Eudicot Clade
Magnoliales Order – Magnoliids Clade
Piperales Order – Magnoliids Clade
Sapindales Order – Eudicot Clade

Welcome to my Plant Families of North America page! I have been absent awhile, but I am back, and this is my focus, teaching how to identify plant families. Over the next few weeks, I will be updating what I have so far. I will be adding new layman’s descriptions in addition to botanical descriptions, and I will be adding more morphology photos, including dissections of flowers where available. Please come back often and see what’s blooming!

A quick overview of basic taxonomy and how I have ordered this site. Plants are given a scientific name composed of two parts, the genus they belong to and the particular species they are. The genus can be thought of like plant cousins, whereas at the species level they are more like siblings. Beyond genus you get the family, which is all of the cousins from all the related families. Above that you get an order, which is like a group of similar families.

Below I have organized the families in their orders so that you can see similarities between related families. When you click on a particular family, you will get the characteristics and morphology pictures that represent that family, along with some of the species I have covered in North America from that family.

Note that most technical words have a hover-over description available, or go to the dictionary of botanical terms to learn more. In no time, you’ll be able to identify plants like a scientist!

Alismatales Order – Monocot Clade

Learn how to identify the Araceae or Arum Family - Plant Families of North America — How to Identify the Araceae or Arum Family

Apiales Order – Eudicot Clade

Learn how to identify the Apiaceae Carrot Family - Plant Families of North America — How to Identify the Apiaceae or Carrot Family

Learn how to identify the Araliaceae Ginseng Family - Plant Families of North America — How to Identify the Araliaceae or Ginseng Family

Caryophyllales Order – Eudicot Clade

Learn how to identify the Amaranthaceae family in North America — How to identify the Amaranthaceae family in North America

Gentianales Order – Eudicot Clade

Learn to Identify the Apocynaceae Family

Lamiales Order – Eudicot Clade

Learn how to identify the Acanthaceae Acanthus Family - Plant Families of North America — Learn to Identify the Acanthaceae Family

Magnoliales Order – Magnoliids Clade

Learn how to identify the Annonaceae or Custard Apple Family - Plant Families of North America — How to Identify the Annonaceae or Custard Apple Family

Piperales Order – Magnoliids Clade

Learn how to identify the Aristolochiaceae family in North America — How to identify the Aristolochiaceae family in North America

Sapindales Order – Eudicot Clade

Learn how to identify the Anacardiaceae family

Other References

Some other great resources for information on North American species:

iNaturalist https://www.inaturalist.org/

Canadensys Plant Search https://data.canadensys.net/vascan/search

Flora of North America https://eflora.org

iNaturalist Plant Search https://www.inaturalist.org/home

USDA Plants Database https://plants.sc.egov.usda.gov/home

Currently Seeking Funding To Continue This Non-Profit, Ad-Free Work

If you are able to donate so that I can continue this non-profit work of supplying people with scientific information on the plant families, native plants, and invasive species found throughout North America, please donate using the GoFundMe link below. Thank you! (COMING SOON)

5 Sep, 2022

How to Identify the Annonaceae or Custard Apple Family

Asimina triloba, American Pawpaw fruit, in flower. Learn how to identify the Annonaceae Family — *Asimina triloba*, American Pawpaw fruit, in flower
Page Last Updated April 28, 2026

Introduction to the Annonaceae Family

The Annonaceae is an interesting family to learn to identify. They are mostly tropical trees and shrubs with unique flowers and fleshy, often edible and delicious fruits. The most well-known member of the Annonaceae in North America is the pawpaw fruit, or Asimina triloba. It is the most northern member of this family and produces delicious fruits that taste similar to bananas. Learn how to identify the Annonaceae family with morphology photos like the flowers shown in the photo above of Asimina triloba, which are typical for the Annonaceae family, with their 6 petals and 3 sepals and their androecium in a ball in the center.

The Annonaceae family is part of the Magnoliales order in the Magnoliids clade of angiosperms, the third largest clade after dicots (eudicots) and monocots. Occasionally this clade is referred to as a ‘peripheral angiosperm’ because it is neither a dicot nor a monocot, where the vast majority of flowering plants are classified. Instead, this clade is characterized by features of both dicots and monocots, including trimerous flowers (monocot) and branching veins (dicot), as well as pollen with one pore.

Common Botanical Description

If you’re new to plant morphology, this guide is a perfect beginner’s description to learning to identify the Annonaceae family, with no need to know any scientific jargon. Below this section is additional information on uses and morphology photos to help you identify the family, followed by pictures of individual species found in North America. But for researchers or those wanting to learn a more in-depth version, refer to the Scientific Botanical Description below the images for highly detailed scientific descriptions and genus-level distribution data.

Leaves and Stems: The Annonaceae family is made of woody trees, shrubs, or vines that may be evergreen or deciduous. They are known for their fibrous and aromatic barks containing essential oils and resins.

Leaves are simple with smooth (entire) edges and are arranged alternately along the stem. The leaves do not wrap around or sheath the stem at their base. And while the leaves are generally odorless, some may be aromatic or dotted with tiny glands.

Flowers: The flowers are arranged singly or in branched clusters, are usually symmetrical, and their parts are usually found in multiples of three, similar to most monocots. However, they generally have a distinct outer layer of sepals and an inner layer of petals, which differentiates them from monocots that have no sepals. This is why they are considered “peripheral” angiosperms since they are neither a monocot or a dicot. These parts often total 9 and are arranged in 3 rings (whorls). The petals are often thick and fleshy and sometimes contain visible nectar glands.

Reproductive Features: The male parts are very distinct, with between 25 and 100 stamens that are packed together in a spiral that forms a characteristic dense ball or flat-topped mass in the center of the flower, which is a good characteristic to help identify the family. The ovary is superior, sitting above the point of where the petals attach.

Fruits: Fruits are usually fleshy aggregates of multiple berries that fuse together to form a larger, secondary fruit that is often edible. The seeds inside are sometimes brightly colored.

Uses of Annonaceae

Many have edible fruits, but they should be eaten with caution, as they contain varying levels of annonacin, which has been implicated in neurodegenerative diseases. Several important tropical commercial fruits come from Annona species (atemoya, cherimoya, custard apple, ilama, sugar apple, sweetsop, and soursop) and Artabotrys.

Medicinal uses include its use as an analgesic and astringent and to treat various conditions, including snakebite, diarrhea, dysentery, arthritis pain, rheumatism, convulsions, neuralgia, and weight loss.

Morphology of Annonaceae in North America

So far in North America, I have only photographed Asimina triloba, since it is the most northern species of this primarily tropical family, but here are some pictures of different morphological aspects of that species.

Learn how to identify the Annonaceae family with morphology photos.

Annonaceae Species I have Covered So Far in North America

So far in North America, I have only photographed Asimina triloba, the morphology photos above show pictures of that species. When I cover more species, I will add more pictures here.

Asimina triloba—American Pawpaw

A large shrub or small tree growing to 11 m with simple, alternate-spirally arranged obovate–lanceolate leaves 25 – 30 cm long with a cuneate base, acute tip, and entire margin. Leaves smell similar to green bell peppers if bruised. Flowers are red-purple or maroon, 3 – 5 cm wide, and borne singly on stout, hairy axillary stalks (peduncles), appearing with or before the leaves in the spring. The fruit is a large yellowish to brown berry 5 – 15 cm long and weighing up to 510 g that is edible and sweet. Native to eastern North America. Click here to read my blog on Asimina triloba

Scientific Botanical Description of the Annonaceae

Flowers of the Annonaceae

Plants are usually hermaphrodite or sometimes dioecious and rarely monoecious. The flowers are usually 3-merous. They are axillary and may be singular or found in racemose, compound inflorescences. The receptacle may be elevated, enlarged, or flat. The outer whorls are inserted below the ovaries. Flowers are regular and cyclic or partially acyclic. Sometimes the androecium is spiraled (acyclic). Free hypanthium is absent, and a hypogynous disk is present. The perianth has a distinct calyx and corolla that may be petaline or made of tepals; however, sometimes it can be difficult to determine when the outer 1-2 whorls are sepaloid. The perianth has 9 (10–12) parts, which may be basally joined or free, is usually 3-whorled, is isomerous, and may be similar or different in the whorls. The calyx has 3 or 6 parts, typically 2 whorled and free (sometimes basally connate), and the lobes are longer than the tube. The corolla has 3 or 6 parts, is 1–2 whorled, is free (sometimes basally connate), and is imbricate or valvate. They may have 6 petals in 2 unequal whorls of 3 with larger outer whorls and fleshier inner whorls that might share the same nectar glands or 6 to 15 petals with impressed veins on the inner face (Annona muricata).

Androecium of the Annonaceae

The androecium contains 25–100 (usually many) members. Androecial members usually mature centripetally, are free of the perianth and each other, are all equal, are usually spiraled, and are rarely 3 or 6 whorled. The androecium is usually made entirely of fertile stamens but may include staminodes (e.g. in Uvaria). Staminodes, when present, are external to the fertile stamens and are non-petaloid. Stamens are inserted below the ovary and arranged spirally, forming a characteristic ball or flat-topped mass of short, stout filaments and linear to oblong anthers that face upwards. Anthers are adnate, non-versatile, dehisce via longitudinal slits or longitudinal valves, are extrorse, are tetrasporangiate, and are appendaged via expansion of the connective.

Gynoecium of the Annonaceae

The gynoecium is 10–100(+) carpeled. When syncarpous, the pistil is 1- or 2- to 15+-celled. It is usually apocarpous (carpels spiraled or cyclic) or synstylovarious to syncarpous (e.g., Monodora); the ovary is superior. The carpel is 1–10-ovuled. Placentation of free carpels is basal. The ovary, when syncarpous, is 1 or 2–15+ locular. Stigmas are wet type and papillate and Group III type. Placentation, when unilocular, is parietal or basal; when plurilocular, it is basal. Ovules in the single cavity when unilocular are 1–50, with 10–50 per locule. Ovules are ascending and apotropous, have a ventral raphe, may be arillate or not, and are anatropous, bitegmic, and crassinucellate.

Fruit of the Annonaceae

The fruit is a fleshy aggregate that is often made of berries. Fruiting carpels may coalesce into a secondary syncarp or they may not. The fruiting carpel is indehiscent and baccate. Seeds are endospermic with 1 to many per pistil and are often brightly colored. The endosperm is ruminate, oily, and has amyloid.

Habit & Leaf Form of the Annonaceae

Trees, shrubs, or lianas that are deciduous or evergreen and produce essential oils and may be resinous. The inner bark is typically fibrous and aromatic, and the pith is septate to diaphragmed. Plants may be self-supporting or climbing. When climbing, they may be scrambling or using stem or petiole twining. Branching is distichous or spiral.

Leaves are typically arranged alternately, are non-sheathing, simple, petiolate, and may or may not be gland-dotted or aromatic. Lamina is entire, pinnately veined (sometimes palmately), and cross-venulate. Leaves are exstipulate. Lamina margins are entire. Domatia occurs in three genera as pockets or occasionally as hair tufts.

Taxonomy of Annonaceae

The Annonaceae family has 2503 species in 108 genera. They are part of the Magnoliales order in the Magnoliids clade of the peripheral (not true dicot or monocot) angiosperms.

The family is divided into 4 subfamilies as follows:

Anaxagoreoideae is a group of 25 species in a single genus found in tropical America and the tropics in and around Indonesia (absent from tropical Africa). They have 2-ranked trunk leaves, sessile stigmas, and dry follicles that are explosively dehiscent.
Ambavioideae is a more widespread group found throughout the tropics and into temperate eastern North America. This subfamily is characterized by a truncate and dilated anther connective, an intine that does not extrude through the aperture, and ovules with a middle integument.
Annonoideae is another mostly tropical subfamily that is rarely found in temperate areas. It is also characterized by an intine that does not extrude through the aperture but can be differentiated based on having a lamelliform ruminate endosperm.
Malmeoideae is restricted to the lowland tropics and is characterized by a glass-like endosperm with ruminations spiniform.

Genera of the Annonaceae Family:

Anaxagoreoideae: Anaxagorea (25).

Ambavioideae: Cananga (2), Cleistopholis (4), Cyathocalyx (7), Drepananthus (28), Lettowianthus (1), Mezzettia (5), and Tetrameranthus (8).

Annonoideae: Afroguatteria (3), Annona (171), Anonidium (5), Artabotrys (111), Asimina (11), Asteranthe (2), Bocagea (4), Boutiquea (1?), Cardiopetalum (3), Cleistochlamys (1), Cymbopetalum (27), Dasymaschalon (31), Dennettia (1), Desmos (19), Diclinanona (3), Dielsiothamnus (1), Disepalum (10), Duckeanthus (1), Duguetia (97), Fissistigma (59), Friesodielsia (53), Froesiodendron (3), Fusaea (2), Goniothalamus (139), Guatteria (186), Hexalobus (5), Hornschuchia (12), Isolona (20), Letestudoxa (3), Lukea (2), Mischogyne (5), Monocyclanthus (1), Monodora (14), Neostenanthera (5), Ophrypetalum (1), Porcelia (7), Pseudartabotrys (1), Pyramidanthe (12), Sanrafaelia (1), Sphaerocoryne (8), Toussaintia (4), Trigynaea (9), Uvaria (170), Uvariastrum (5), Uvariodendron (18), Uvariopsis (18), and Xylopia (197).

Malmeoideae: Alphonsea (39), Annickia (11), Bocageopsis (4), Brieya (2), Cremastosperma (31), Dendrokingstonia (3), Desmopsis (46), Ephedranthus (7), Fenerivia (11), Greenwayodendron (6), Huberantha (35), Klarobelia (14), Leoheo (1), Maasia (6), Malmea (7), Marsypopetalum (5), Meiocarpidium (1), Meiogyne (39), Miliusa (67), Mitrephora (53), Mkilua (1), Monanthotaxis (94), Monocarpia (4), Monoön (80), Mosannona (14), Mwasumbia (1), Neo-uvaria (7), Onychopetalum (2), Orophea (61), Oxandra (29), Phaeanthus (9), Phoenicanthus (2), Piptostigma (13), Platymitra (2), Polyalthia (98), Polyalthiopsis (5), Polyceratocarpus (11), Popowia (29), Pseudephedranthus (2), Pseudomalmea (4), Pseudoxandra (24), Pseuduvaria (60), Ruizodendron (1), Sageraea (9), Sapranthus (10), Sirdavidia (1), Stelechocarpus (3), Tridimeris (10), Trivalvaria (13), Unonopsis (48), Wangia (2), and Wuodendron (1).

Key Differences From Similar Families

The Annonaceae is easily distinguished from other Magnoliales by its fibrous and aromatic bark. Myristicaceae can be differentiated by their red latex. Magnoliaceae can be differentiated by their large deciduous stipules.

Distribution of Annonaceae

Mostly subtropical and tropical, rarely temperate. Widespread, especially in the Old World. In the Americas, it is found all over the Neotropics and north as far as southern Canada. It is particularly common in lowland forested areas.

Distribution of Annonaceae in the Americas

Canada Genera:

Annonoideae: Asimina 1 E NAM endemic spp. native to southern ON, the northernmost Annonaceae in the world.

USA Genera:

Annonoideae: Annona 3 spp. native to FL; Artabotrys 1 sp. introduced in HI; Asimina 11 E NAM endemic spp. native to the E USA from ND S to TX and all states E excluding ND, SD, MN, CT, RI, VT, NH, and ME; Deeringothamnus monospecific endemic of FL; Polyalthia 1 sp. intro to FL.

Mexico Genera:

Anaxagoreoideae: Anaxagorea 1 sp. native to SW Mexico, Ver. Ambavioideae: Cananga 1 sp. intro to SW Mexico, Ver. Annonoideae: Annona 14 spp., including 12 native all through Mexico and 1 sp. introduced to Sin, east to Tam, and south to Oax, Chp, QR, and Yuc; Cymbopetalum 2 spp. native to Chp, Ver, and Oax?; Guatteria 2 spp. are native to SW+SE+S Mexico, Ver; Xylopia 1 sp. native to S Chi. Malmeoideae: Desmopsis 20 spp. inc. 19 endemic to rainforests of SW+SE Mexico and Ver; Mosannona 1 sp. native to Cam, Chp, QR, Ver, Yuc; Oxandra 4 spp. native to SW+C+SE Mexico and Ver, including 1 narrow endemic of Chp; Sapranthus 3 ~neoendemic spp. native Gro, Oax, QR, Sin, Chp, and Ver, including 1 narrow endemic of Chp;Tridimeris 10 Mexican endemic spp. native to E+C Mexico including 1 narrow endemic of Chp; Unonopsis 2 neoendemic spp. native to SW+SE Mexico, including 1 endemic to Oax; Uvaria 1 of 168 Old World Tropics spp intro Jal;

Neotropical Genera:

Anaxagoreoideae: Anaxagorea 22? spp. native CAM (exc. El Salvador), Trinidad-Tobago, tropical SAM S to Peru, Bolivia, and C+SE Brazil, including 5 narrow endemics of Costa Rica & Panama, S Venezuela (2), N Peru, and SE Brazil. Ambavioideae: Cananga 1 sp. intro Guatemala, Nicaragua, Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is., and Trinidad-Tobago; Tetrameranthus 8 N SAM endemic spp. of N Brazil, Colombia, Venezuela, French Guiana, Ecuador, and Peru. Annonoideae: Annona ~160 spp., mostly endemics also widely cultivated throughout CAM, Bahamas, Antilles, SW Caribbean, tropical SAM S to N Argentina (excluding Chile); Artabotrys 1 sp. intro to Bahamas, Leeward Is., Windward Is, and Trinidad-Tobago; Bocagea 4 spp. endemic to E Brazil; Cardiopetalum 3 N SAM endemic spp. of Suriname, French Guiana, N+C+E Brazil, Peru, and Bolivia; Cymbopetalum 27 Mexico + Neoendemic spp. native from S Mexico S through CAM and tropical SAM S to Peru, Bolivia, C+E Brazil; Desmos 1 sp. intro to C+E Brazil and Trinidad-Tobago; Diclinanona 3 N SAM endemic spp. native N+C Brazil, Colombia, Peru, and Venezuela; Duckeanthus monospecific narrow endemic of N Brazil; Duguetia 91 spp. native from Nicaragua S through tropical SAM S to Peru, Bolivia, Paraguay, S Brazil (+4 spp. endemic to W Africa); Ephedranthus 7 SAM endemic spp. native to tropical SAM S to Peru, Bolivia, Paraguay, SE Brazil (exc. Ecuador); Froesiodendron 3 N SAM endemic spp. native to Colombia, Peru, and N Brazil; Fusaea 2 N SAM endemic spp. native to N+NE+C Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, Venezuela, and Bolivia; Guatteria 186 neoendemic spp. native from S Mexico S through CAM (excluding El Salvador), Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is, tropical SAM S to Peru, Bolivia, C+S Brazil; Hornschuchia 12 narrow endemic spp. of E. Brazil; Monodora 1 sp. intro Trinidad-Tobago; Porcelia 7 neoendemic spp. of Costa Rica, Panama, Colombia, Venezuela, N+E+S Brazil, Ecuador, Peru, and Bolivia; Trigynaea 9 N SAM endemic spp. native to Colombia, Venezuela, Guyana, Suriname, N+E Brazil, Ecuador, Peru, and Bolivia; Uvaria 1 sp. intro to Trinidad-Tobago; Xylopia 40 spp. native to CAM, Cuba, Jamaica, Trinidad-Tobago, tropical SAM S to Peru, Bolivia, NE Argentina. Malmeoideae: Bocageopsis 4 SAM endemic spp. native to Colombia, Venezuela, Guyana, Suriname, French Guiana, N+C+S Brazil, Peru, and Bolivia; Cremastosperma 34 neoendemic spp. native to Costa Rica, Panama, Colombia, Venezuela, N+C Brazil, Ecuador, Peru, and Bolivia, with most diversity in the narrow tropical zone W of the Andes; Desmopsis 27 spp. native from S Mexico S through all of CAM to Colombia, including narrow endemics in Cuba (1), Costa Rica (4), Colombia (3), Honduras (3), and Panama (3). Klarobelia 14 neoendemic spp. native from Costa Rica S to Colombia, Venezuela, N Brazil, Ecuador, Peru, Bolivia, including several endemics to Ecuador; Malmea 7 neoendemic spp. native to Panama, Colombia, Guyana, Suriname, N+NE Brazil, and Peru; Monoön 1 sp. intro Trinidad-Tobago; Mosannona 14 Mexico + neoendemic spp. native to Guatemala, Belize, Honduras, Costa Rica, Panama, Colombia, N Brazil, Guyana, Suriname, Ecuador, Peru, and Bolivia, including 6 narrow endemics of Costa Rica, Barro Colorado Is. Panama, Guatemala, Suriname and Guyana, and Ecuador; Onychopetalum 2 SAM endemic spp. of Venezuela, N+C Brazil, Peru, and Bolivia; Oxandra 28 Mexico + neoendemic spp. native from S Mexico, Guatemala, Belize, Nicaragua, Costa Rica, Panama, Greater Antilles (excluding Cayman Is), Leeward + Windward Is, SW Caribbean, tropical SAM S to Peru, Bolivia, C+SE Brazil, including 9 narrow endemics of Colombia (3), Suriname, Guyana, Brazil (4); Polyalthia 1 sp. intro to Trinidad-Tobago; Pseudephedranthus 2 N SAM endemic spp. of Venezuela, Guyana, Suriname, and N Brazil; Pseudomalmea 4 N SAM endemic spp. of Colombia, Venezuela, N Brazil, Ecuador, Peru, and Bolivia; Pseudoxandra 24 tropical SAM endemic spp. native to Colombia, Venezuela, Guyana, French Guiana, N+C Brazil, Peru, and Bolivia; Ruizodendron monospecific neoendemic of Colombia, N Brazil, Ecuador, Peru, Bolivia, and disjunct Honduras?; Sapranthus 9 Mexico + N neoendemic spp. native to CAM and Colombia, including 1 narrow endemic of Cesar Colombia; Unonopsis 47 neoendemic spp. are native from S Mexico, CAM (excluding El Salvador), and tropical SAM S to Peru, Bolivia, and C+S Brazil;

Patagonia Genera:

Absent

Additional Information and References

Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
Willis, Lyrae (Unpublished). Plant Families of North America. Below should be most of my references for this along with my own personal observations in North America.
Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
Cruz-Chacon, Ivan de la Marisol Castro-Moreno, Lorena Mercedes Luna-Cazares, and Alma Rosa Gonzalez-Esquinca (2016). La Familia Annonaceae Juss. en México. Lacandonia, year 10, vol. 10, num. 2: 71-82, December 2016.
Delta: Watson, L., and Dallwitz, M.J. (1992+). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
GBIF.org (2020), GBIF Home Page. Available from: https://www.gbif.org
Naturalista: CONABIO http://www.naturalista.mx (Accessed 2020–current).
Neotropikey: Milliken, W., Klitgård, B. & Baracat, A. eds. (2009+). Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
POWO (2019). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet: http://www.plantsoftheworldonline.org/ Retrieved Winter 2020-current.
USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; accessed throughout the fall of 2020.
WFO (2022): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

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They are non-laticiferous without colored juice, with or without essential oils, and resinous.

5 Sep, 2022

25 Aug, 2022

Cypripedium acaule Pink Lady's Slipper Orchid

Cypripedium acaule the Pink Lady Slipper or Moccasin Flower - photo from Allatoona Creek, Georgia by Lyrae Willis — *Cypripedium acaule* the Pink Lady Slipper or Moccasin Flower – photo from Allatoona Creek, Georgia by Lyrae Willis

Pink Lady Slipper or Moccasin Flower Cypripedium acaule
Introduction
Description of Cypripedium acaule
Similar Species Frequently Confused With
Distribution of Cypripedium acaule
Habitat & Growing Conditions of Cypripedium acaule
Growing Pink Lady Slipper in Your Garden
Wildlife Values of Cypripedium acaule
Status of Cypripedium acaule
Traditional or Other Uses of Pink Lady Slipper
Ethical Wildcrafting of Cypripedium acaule
References and Resources

Pink Lady Slipper or Moccasin Flower Cypripedium acaule

Introduction

These gorgeous orchids are always a lovely treat when you find them growing in the forest. Fortunately, they are not excessively rare, though they are not all that common either. Cypripedium acaule is part of the Cypripedioideae subfamily in the Orchidaceae family. It goes by two common names the Pink Lady Slipper Orchid or the Moccasin Flower after their slipper or moccasin-shaped flowers that are unique to their genus. Orchids everywhere are declining in population due to habitat loss, climate change, and highly specific pollination with poor overall pollination rates. If you do find these please never pick the beautiful flowers. Instead, leave them there to hopefully be pollinated and produce the next generation. Take out your phone and take pictures of the beautiful flowers instead. You can put them on your computer desktop or print them and frame them for your wall and enjoy them for many years.

Description of Cypripedium acaule

Stem & Leaves

Pink Lady Slippers are erect herbaceous perennials 15 – 60 cm tall with solitary flowers on a leafless peduncle (flower stalk).

Two leaves grow opposite from each other directly from the rhizome. They are ovate or broadly elliptic to oblong in shape and measure 9 – 30 cm long and 2.5 – 15 cm wide. Rarely plants will only have one leaf.

Young leaves of Cypripedium acaule; photo from Allatoona Creek, Georgia, USA — Young leaves of *Cypripedium acaule*; photo from Allatoona Creek, Georgia, USA

Flower closeup of Cypripedium acaule showing the vertical slit in the pouch; Allatoona Creek, GA, USA — Flower closeup of *Cypripedium acaule* showing the vertical slit in the pouch; Allatoona Creek, GA, USA

Flowers & Fruits

The showy solitary flowers bloom from April to July. They have tepals (sepals and petals) that are yellowish-brown, reddish-brown, pinkish, or even green. They are deflexed or spreading and may be slightly twisted, and are 1.9 – 5.2 cm long. The lip (labellum) is located below the tepals and is shaped like a large pouch with a slit down the middle, slipper or moccasin-like. It is usually a light pink but occasionally may be magenta and is obovoid in shape, 3 – 6.7 cm long.

Toxicity

The Cypripedium genus all have glandular hairs on the leaves and stems. The compound in the hairs can cause contact dermatitis similar to poison ivy.

Similar Species Frequently Confused With

It is difficult to confuse Cypripedium acaule for most other genera due to the unique moccasin-like lip on the flower. Sometimes people do mistake flowers of other genera, but if you just look for the distinctive labellum or lip that is shaped like a pouch with a slit down the middle, you can tell for certain it is a Cypripedium. So, most misidentifications are with other members of the same genus. Other Cypripedium species can be differentiated as follows:

Cypripedium reginae Showy Lady Slipper has a more limited range from Saskatchewan east to Newfoundland Island in Canada and the northern US from Minnesota south to Arkansas and east to Maine, but mostly concentrated in the states that border Canada. It is taller, growing to 100 cm, and usually sprouts many stems from the same rhizome. Showy Lady Slipper has more leaves, with 3 – 5 leaves per stem. It also has larger and much more showy white tepals and usually a brighter pink or magenta lip.
Cypripedium parviflorum Yellow Lady Slipper is another largely eastern North American species that extends to the Canadian Rockies and Arctic in the west and the Rocky Mountains in the US states. Otherwise, it has a very similar eastern range as Cypripedium reginae. It is fairly easy to tell apart, however, since its lip is always yellow.
Cypripedium candidum Small White Lady Slipper has a limited range and is listed as a Vulnerable species globally. It is rare and endangered in Canada but can be found in the extreme southern parts of eastern Canada from Saskatchewan east to Ontario. In the US, it is also rare and vulnerable and can be found from North Dakota south to Nebraska and east to New York, with some also found from Missouri south to Alabama. It is a much smaller plant, only up to 36 cm tall, and has a smaller lip that is always white.
Cypripedium montanum Mountain Lady Slipper is another rare vulnerable orchid that is found in the Pacific Northwest from Alaska south to northern California and east to the Alberta Rocky Mountains in Canada and Montana in the US. It is typically found only at high elevations in open forests and subalpine slopes. It grows to 70 cm tall and has 1 – 3 large flowers on top of its stem, and its pouch is always white.

Distribution of Cypripedium acaule

Moccasin Flower is a central and eastern Canadian and eastern USA species. It is not found anywhere else in the world.

In Canada, Cypripedium acaule is found in Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland Island (not Labrador). It may also be present in the Northwest Territories.

In the USA, Pink Lady Slipper is found in Minnesota, Wisconsin, Illinois, Michigan, Indiana, Michigan, Indiana, Ohio, Kentucky, Tennessee, Alabama, Georgia, North & South Carolina, Virginia, West Virginia, Pennsylvania, Delaware, Maryland, Washington DC, New York, New Jersey, Connecticut, Rhode Island, Massachusetts, Vermont, New Hampshire, and Maine.

Habitat & Growing Conditions of Cypripedium acaule

Cypripedium acaule tolerates a wide range of shade and moisture conditions being found in dry to wet forests, shrublands, and slopes, but it prefers partial shade and well-drained slopes. However, it requires highly acidic soils, which is probably why it is often found in pine forests but can be seen in deciduous and mixed woods as well. It is generally found below 1200 m in elevation.

Growing Pink Lady Slipper in Your Garden

Cypripedium acaule is challenging but not impossible to grow yourself if you don’t already have a highly acidic or coniferous forest to plant them in. For a long time, it was believed that it could not be cultivated due to a belief that a fungal association found in the forest was required for germination and growth. However, Pink Lady Slipper is available commercially but is not easy to find as it is more difficult to grow than other species. You will not be able to grow it from seed as special conditions and fungal associations are still required for germination, but once it has true leaves, it can be moved into a garden.

To grow commercially purchased plants of Cypripedium acaule, the only real critical factor is soil pH. It absolutely must be kept below 5.0 to prevent the plants from rotting from the activity of soil microbes that increase above pH 5.0. Anywhere from 4.0 – 4.5 pH is ideal for Pink Lady Slipper. To keep the pH so low, you must grow them in a container so that you can better control the conditions. Use a significant amount of peat moss or pine duff in the soil and use pH-neutral perlite to improve drainage. Tap water should never be used to water them due to the risk of Calcium in the water that would raise the pH. Instead, use rainwater or distilled water mixed with 2 oz of vinegar per gallon.

Other things to consider are where to place the pots. Ideally, morning sun or dappled sunlight under a tree is best. And be sure to sink the pots into the ground in winter or store them in a cold frame.

Wildlife Values of Cypripedium acaule

Native bees routinely visit the flowers.

Status of Cypripedium acaule

Pink Lady Slipper is currently listed as Least Concern on the IUCN Red List. However, as with most woodland plants, the population of mature individuals being found is decreasing.

NatureServe lists Moccasin Flower as Globally Secure, G5.

In Canada, Pink Lady Slipper is considered Locally Secure S5 in Ontario, Quebec, New Brunswick, Nova Scotia, and Prince Edward Island. It is Apparently Secure S4 in Saskatchewan and Newfoundland Island. In Alberta and Manitoba, it is Vulnerable S3.

In the USA, Cypripedium acaule is considered Locally Secure S5 in West Virginia, Virginia, and North Carolina. It is considered Apparently Secure S4 in Kentucky, Tennessee, New York, New Jersey, Delaware, Connecticut, and Georgia. In Alabama, it is considered Vulnerable S3. It is considered Critically Imperiled S1 in Illinois and Indiana. In all other states where it is found, its status is not yet determined.

Traditional or Other Uses of Pink Lady Slipper

Cypripedium acaule Medicinal Uses

Pink Lady Slipper roots were used by the Algonquin for stomachaches, menstrual disorders, kidney and urinary infections, and venereal diseases. Cherokee used the root as an analgesic, anticonvulsive, to treat colds, flu, stomachaches, kidney problems, worms, and ‘female trouble’. Iroquois used them in a decoction as an analgesic and in a poultice for bite wounds. Menominee used it to treat urinary problems and ‘male disorders’. Micmac and Penobscot used the root as a sedative for nervousness. Rappahannock used the dried roots in whiskey as a panacea for general ailments.

Pink Lady Slipper as an Ornamental

Due to the challenges of growing it this plant is only occasionally grown as an ornamental. But for the most serious and dedicated gardeners or orchid lovers, it is a lovely addition to any woodland garden.

Ethical Wildcrafting of Cypripedium acaule

Check the status in your state before harvesting since it is vulnerable in some areas. See the above section on Status. Alternatively, grow it in your garden but do not attempt to harvest wild plants to transplant to your garden as, most likely, you will simply be killing the plant. Instead, buy commercially available plants that have been germinated in an orchid lab.

Generally speaking, I do not recommend wildcrafting this plant in any form. Transplanting has a poor survival rate, and the only other reason for harvesting is the root to be used medicinally. If using this root is part of your traditional heritage, and you want to harvest some, always use the 1 in 20 rule of Ethical Wildcrafting. Harvest the roots of only one in every plant you see in an area where they are locally common.

Wildcrafting and Processing

Use a digging stick to loosen the roots from the soil. Picked roots can be placed in a basket, bowl, or paper bag and brought home for processing. If you are harvesting multiple products on the same day, be sure to label the roots in a paper bag so that you do not confuse different plants.

Roots should be brushed clean of any dirt and then chopped into more manageable pieces before drying. Dried roots are notoriously difficult to cut into smaller pieces once dried.

Once dried, the roots can be stored in a jar for later use. Label your jar with the species name and the date, and I also usually add the location of the harvest for my own reference. Do not grind or crush the leaves or roots until you are ready to use them. This will keep them as fresh as possible to preserve their medicinal properties. When you pre-grind, even if stored in glass jars, this increases the oxidation rate and rapidly degrades the medicinal properties reducing their useful shelf-life.

References and Resources

Canadensys Plant Search https://data.canadensys.net/vascan/search

Dictionary of Botanical Terms – by Lyrae’s Nature Blog https://lyraenatureblog.com/blog/dictionary-of-botanical-terms/

Flora of North America https://eflora.org

iNaturalist Plant Search https://www.inaturalist.org/home

IUCN Red List https://www.iucnredlist.org/

Lady Bird Johnson Wildflower Center https://www.wildflower.org

Native American Ethnobotany http://naeb.brit.org/

NatureServe Explorer https://explorer.natureserve.org/Search

USDA Plants Database https://plants.sc.egov.usda.gov/home

Willis, Lyrae (? Not yet published). Plant Families of North America.

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25 Aug, 2022

22 Aug, 2022

Carduus nutans Musk Thistle - Invasive Species of North America

Carduus nutans floral bug from Knoxville, TN. Photo by Lyrae Willis 2021. — *Carduus nutans* floral bug from Knoxville, TN. Photo by Lyrae Willis 2021.

Introduction
Description of Carduus nutans
Similar Species Frequently Confused With
Native Distribution of Carduus nutans
Habitat Types Where Carduus nutans is Found
Human Uses of Musk Thistle
Distribution of Carduus nutans in North America
How Carduus nutans Spreads
Habitats at Risk of Invasion in North America
Impacts of Invasion
Methods to Remove Carduus nutans
Physical Control of Nodding Thistle
Chemical Control of Carduus nutans
Biological Control of Musk Thistle
Integrated Pest Management & Ongoing Monitoring
References and Resources

Introduction

Carduus nutans also known as Musk Thistle or Nodding thistle is a widespread invasive species found throughout most of southern Canada and almost the entire USA. It is a herbaceous biennial plant in the Carduoideae subfamily of the Asteraceae (Sunflower) family. While in cooler climates it typically takes 2 years to produce seeds before the plant dies in warmer climates it may grow and go to seed in a single season. It is frequently found on roadsides, in pastures, meadows, empty lots, disturbed land, and waste places throughout its range.

Description of Carduus nutans

Leaves & Stems

These biennial plants at maturity will reach 150 – 250 cm tall and typically have multi-branched stems. Occasionally single-stem specimens can be found under poorer conditions or in areas with lots of competition. The stems are covered with spines and a woolly covering of hair with occasional small leaves. Stems and leaves sprout from a stout taproot up to 40 cm long.

Leaves develop from a basal rosette and reach 40 cm long when mature. When young the leaves are somewhat lobed and slightly pubescent hairy and more or less upright but as they mature they become prostrate and more heavily pinnately lobed and have prominent sharp yellowish to whitish spines at the lobe margins. The surface is dark green, waxy, and pubescent (hairy) on top with woolly veins on the lower surface.

Flowers & Fruits

Carduus nutans flower from the Lincoln National Forest, NM. Photo by Lyrae Willis 2022. — *Carduus nutans* flower from the Lincoln National Forest, NM. Photo by Lyrae Willis 2022.

Flowers form in large globose heads made of hundreds of tiny but showy reddish-purple disk flowers. Rarely, white variants can be seen. Flower heads are 3 – 5(-7) cm in diameter and form at the end of the stems. Upright immature heads begin to droop as they mature at 90° to 120° from the stem. Heads are surrounded by woolly spiny tipped phyllaries that often are purplish. Outer phyllaries reflex at maturity while the rest of them are constricted in the middle with blades that are narrower than their bases.

Fruits are cypselae which are typical for the Asteraceae family. They consist of a small angled seed (frequently mistaken for an achene) 3 – 4.5 mm long that is gold, fawn, or brown with fine wrinkles and a white pappus of numerous hairs up to 2 cm long. These fruits are suitable for dispersal by wind due to the small light seeds and light pappus that catch wind currents. Each flower head produces hundreds up to 1200 cypselae.

Similar Species Frequently Confused With

There are many thistle species in North America that Carduus nutans may be confused with. Some are native and some are introduced. Following is a list of the most similar-looking species and how you can differentiate them.

In the Carduus genus we have:

Carduus acanthoides the Broad-Winged Thistle found in the eastern USA and Canada, central USA, and south-western Canada. Native to Eurasia it has similar leaves and growth habits but the flower heads are smaller and not globose or nodding like Carduus nutans. Instead, its mature flowers are more or less erect, 1.3 – 2.5 cm across and its achenes have a pappus that is 1.1 – 1.3 cm long. Hybrids between the two species have been observed in some of the eastern US states which may make identification difficult. However, since no Carduus species are native to North America this should not be a problem for control purposes as long as it is identified to the genus level.

Most of the other less closely-related species that also look similar are in the Cirsium genus. They can be differentiated as follows:

Cirsium vulgare the Bull Thistle is also Eurasian and occupies almost the exact same range as Musk Thistle but extends further into Mexico and in the US is found in Vermont and Maine as well. It is fairly easy to tell apart, however, by its much more bulbous-shaped receptacle and smaller phyllaries that have many more layers and are more appressed to the receptacle. The flower heads are less rounded and generally a bit smaller than Nodding Thistle. Leaves are more of a grey-green and are generally smaller to only 30 cm.
Cirsium arvense the Creeping Thistle is native to Eurasia and is now found throughout the northern half of the USA and most of southern Canada and some in the northern Territories and eastern Alaska. It tends to grow in clonal colonies by sending up shoots that grow into plants on more slender stems to only 150 cm tall that are smooth and hairless and generally not spiny. The spiny leaves are smaller only 20 cm long. Flower heads are also much smaller only 2.2 cm wide which grow in clusters on the tops of stems instead of singly.
Cirsium horridulum the Bristle Thistle is a native plant found in the eastern US from New England south to Florida and west to Texas and Oklahoma as well as parts of Mexico and eastern Central America. It grows to similar heights and has leaves of similar sizes but the often purple-tinged leaves have thicker spines that are more densely placed on the leaves and up the stem. Flower heads are also much spinier and disk flowers may be pink, reddish, white, or even yellow.
Cirsium pumilum the Pasture Thistle is native to the north-central and northeastern USA as well as in Ontario, Canada. It only grows to 100 cm tall and its leaves are shorter to 30 cm long. It has a much longer narrowly egg-shaped receptacle with more rows of phyllaries that are not reflexed. Flowers may be pink, purple, or white and flower heads are less dense generally containing fewer than 100 disk flowers.
Cirsium pumilum the Wavy Leaf Thistle is native to most of western North America from BC east to Manitoba, Canada, and south to Durango, Mexico. It grows to similar heights but is typically less branched, if at all. Its leaves are much more undulated, more shallowly lobed, and grey rather than dark green. The flower heads are of similar size but generally much lighter pink or even white and the receptacle is much more elongated with more appressed phyllaries.
Cirsium ochrocentrum the Yellow Spine Thistle is native to the Central Plains and western deserts of the US and northern Mexico. It grows to only 100 cm tall and its deeply lobed and spiny leaves only grow to 25 cm long. Its phyllaries are appressed to the receptacle and they are tipped with yellow spines. Flower heads contain white, pink, or lavender disk flowers.
Cirsium texanum the Texas Thistle is native to the south-central US and northern Mexico. It is much smaller growing to only 80 cm tall and it has light purple or light pink disk flowers. Its phyllaries are not reflexed and are green and white and tipped with spines. The leaves have fewer spines and are dark green above but woolly white below.
Cirsium discolor the Field Thistle is native to central and eastern Canada and the US. It grows to 200 cm tall but can easily be distinguished by its always solitary stem and its leaves that are green above but white and woolly below.
Cirsium edule the Edible Thistle is native to the Pacific Northwest from Alaska south to Oregon and east to Idaho. Along with its narrow range, it can easily be distinguished by its spiny reflexed arachnoid phyllaries (covered with a mass of downy white hair).
Silybum marianum the Milk Thistle is native to Eurasia but can be found in North America mostly in the coastal states on both the Atlantic and Pacific side with fewer plants in the central regions though they are still present. The easiest way to tell this one apart is by its distinctly variegated leaves mottled in pale green and white. To learn more about this invasive species check out my blog at https://lyraenatureblog.com/blog/milk-thistle-silybum-marianum/

Native Distribution of Carduus nutans

Musk or Nodding Thistle was originally native to much of Europe and western Asia as well as northern and eastern Africa where it grew in fields, meadows, and disturbed habitats.

Habitat Types Where Carduus nutans is Found

Carduus nutans typically grow in meadows and grasslands and are often found in heavily grazed pastures. Stout taproots allow it to easily survive in pastures as it can be more resistant to drought than other pasture plants. It is also found in any disturbed open soil such as roadsides, cleared land, and waste sites. Areas subject to natural disturbances such as landslides and flooding are also suitable habitats.

Carduus nutans prefers open sun and will not grow in excessively wet or dry areas or shady sites such as under the forest canopy. It tolerates neutral or acidic soils and grows from sea level to 2500 m elevation.

Human Uses of Musk Thistle

The pith of the stem can be boiled and eaten like asparagus and is said to have a pleasant taste.

Medicinally the flowers are sometimes used to lower fevers and as a blood purifier. In India studies done with the linoleic acid in the seed’s oil have been shown to help prevent atherosclerosis.

Distribution of Carduus nutans in North America

The species was first accidentally brought to eastern North America in the mid-1800s likely in a ship’s ballast water. Since then it has become very widespread and is found in most US states and most of southern Canada.

In Canada, Carduus nutans have been recorded in most of the southern provinces including British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, and Nova Scotia. Its status in Newfoundland is uncertain and it has not been reported in Prince Edward Island or Labrador nor in any of the Arctic territories.

In the USA, Musk Thistle is found in most of the continental USA excluding only Vermont, Maine, and Florida. It is also not currently found in Alaska or Hawaii.

In Mexico, Carduus nutans so far have only been reported in Mexico City and Mexico State. Given its proximity to the northern border, and the as-of-yet under-reporting of invasive species in Mexico this information will change in the near future.

Musk Thistle has been introduced on every continent except for Antarctica. It has been declared a noxious weed in Canada, the USA, Australia, New Zealand, and South Africa.

How Carduus nutans Spreads

Propagation is strictly by seed. Seeds remain viable for only a couple of years on the soil surface. However, if seeds are buried 20 cm they can last up to 80 years in the soil seed bank.

It is currently primarily spread through long distances as a contaminant in uncertified seeds sold out of the country. Within the same country, long-distance dispersal also results from seeds carried as a contaminant in hay as well as on equipment and vehicles.

Short-distance dispersal occurs through seeds dispersed short distances by wind or transported on vehicles, equipment, etc.

Habitats at Risk of Invasion in North America

Carduus nutans prefer meadows, fields, pastures, disturbed ground, farmland, and any open land with good exposure to sunlight. Since it grows up to 2500 m elevation all open areas to this elevation are at risk. Mature forests, permanent wetlands, and deserts are not at risk as they will not grow in the shade or in permanently wet or excessively dry soil.

Impacts of Invasion

In pastures and farmlands, Carduus nutans can negatively impact production by suppressing the growth of more desirable plants through competition. Carduus nutans plants do well in pastures because of the deep thick taproots that allow them to outcompete grasses and other forage plants for water and nutrients. Furthermore, in dense mature stands, they can become a physical barrier to livestock due to their thick sharp spines.

In natural environments, Musk Thistle can outcompete native plants for resources thereby reducing biodiversity. They can also become a barrier to native animals that live there.

They can also be a barrier in recreational areas impeding hiking, swimming, and other recreational activities.

Potential Benefits of Invasion

Musk Thistle is of benefit to bees, hoverflies, and butterflies that visit the flowers. The plant is also a food source for numerous caterpillars in the Lepidoptera order.

Methods to Remove Carduus nutans

As always prevention is the preferred method of control. While Musk Thistle is never intentionally planted by people it can be unintentionally introduced in uncertified seeds. This is particularly common in seeds imported from other countries with less strict guidelines on seed purity and invasive species. Do not buy or plant poor-quality seeds.

An important source of infestation is in hay fields and pasture land. One method to help prevent their infestation is to plant more drought-tolerant species so that they are less likely to be outcompeted by Carduus nutans. Furthermore, avoiding over-grazing during periods of drought will help prevent them from successfully spreading.

Physical Control of Nodding Thistle

Once already established, however, physical control is always the most effective means. Physical control is labor-intensive and time-consuming but it usually causes the least amount of environmental damage.

The best time to remove Carduus nutans is when the plants are young or during flowering but before they have gone to seed. If your plants have seeds it is best to manually cut the seed heads off into a garbage bag to prevent them from spreading. Once the seed heads have been cut the plants can be dealt with by other physical means.

Physical methods to remove Nodding Thistle in less dense stands involve digging the plants up. This can be done with a shovel or hoeing the ground to 10 cm below the soil surface to ensure that the tap root is sufficiently removed or damaged. Fortunately, the plant cannot survive once a sufficient amount of its taproot has been removed. This works for both young and mature plants.

Mowing can be used on larger populations of Carduus nutans just prior to going to seed. The mowing will need to be repeated each month during the growing season due to the variation of maturity in the plants. Young plants that have not started blooming will not be affected by mowing so the area will need to be mowed for at least 2 – 3 years.

Disposal of the Plants Once Removed

If you have removed the seeds or have removed plants that are not yet in seed they can be disposed of in a compost heap or left on the soil where removed. Carduus nutans can only reproduce by seed so the rest of the plant is not a disposal concern. However, if you have plants that have seeds on them they must either be burned or solarized. To solarize put the shrubs under a thick black tarp, or into thick black garbage bags and leave them in the full sun for 8 weeks at least to be sure that all seeds are no longer viable.

Chemical Control of Carduus nutans

Chemical applications are almost never an ideal method of control for any invasive species. That is because chemical alteration of the environment often makes the environment more suitable for invasive species than native species. Furthermore, it is often difficult to keep the chemical control method contained so that it does not directly affect any native species that are there during the application process itself. As a result, plots where chemical control is used usually show a decrease in species richness. On the other hand, in plots where only physical control is used species riches significantly increase.

If using chemical control it must be done when the plants are young, actively growing, and before the basal rosettes get too large. This makes adequate timing in spring imperative. Furthermore, repeated applications in New Zealand are starting to show resistance to herbicides.

Chemical control is not recommended.

Biological Control of Musk Thistle

Biological control involves the use of a predator, herbivore, disease, or some other agent to control an invasive species once it is established in the environment. The problem with biological control is that the agent used must be entirely specific to only the target organism before releasing it into the environment. This is often difficult to determine since the agent of control is also not native to the environment and could behave differently when released there. Take the example of the mongoose and the rat. The mongoose was released in Hawaii in the late 1800s to help control the rat. To this day there are still rats in Hawaii but the mongoose has helped to decimate many native bird populations.

Biological control methods are extremely risky and should only be carried out by professionals after years of rigorous study. The use of biological control methods can never be used alone. They must be part of an integrated pest management approach. However, using biological control in conjunction with physical control and ongoing monitoring can be very effective. Following is a list of biological control methods that have been used in North America in an attempt to help control Carduus nutans.

Rhinocyllus conicus is a weevil that has been introduced to fight Carduus and several other invasive thistle species including those in the Cirsium genus. The problem in North America is that we have several native Cirsium species so the use of this method is not recommended by some scientists. Furthermore, the success rate has had mixed results so the benefits may not outweigh the risk.
Trichosirocalus mortadelo is perhaps a better choice as it is probably restricted to Carduus nutans and it has been used with some success in Canada, the USA, Australia, and New Zealand. There is still some confusion as there may have also been T. horridus introduced and it is uncertain as of yet which one is effective or more effective. More research is ongoing.
Domestic goats are not selective in their choice of forage greens and will eat anything including Carduus nutans. Domestic goats can be used in pasture lands to help control the spread of Nodding Thistle. They can also be penned in smaller areas and used in conjunction with physical removal and ongoing monitoring.

Integrated Pest Management & Ongoing Monitoring

Integrated management is always the best approach. In its simplest and least impactful form this involves physical removal methods, possibly biological control methods, replanting with drought-tolerant species, and ongoing monitoring. Integrated management is required because the area needs to be monitored for new or surviving plants otherwise all the hard work done in removal could be wasted if the invasive species is allowed to regrow.

Replanting is Crucial

In all cases of large-scale physical removal, the site should be replanted immediately because the bare soil will allow the seed bank to germinate and reinvade the patch they were removed from. A replanting program should already be planned and ready to implement immediately upon the removal of the Carduus nutans.

Ongoing Monitoring is Essential

In all cases of invasive Musk Thistle removal, ongoing monitoring is absolutely essential. Since they only reproduce by seed an aggressive monitoring program is not necessary. Apart from the repeated monthly mowings suggested in the physical removal of large patches most monitoring programs can be simply done on a yearly basis. Each year check for any surviving or new individuals and remove them so that they are not allowed to set seed.

References and Resources

CABI on Carduus nutans https://www.cabi.org/isc/datasheet/11259

Canadensys Plant Search https://data.canadensys.net/vascan/search

Dictionary of Botanical Terms – Lyrae’s Nature Blog Dictionary of Botanical Terms

Eflora Plants of North America http://www.efloras.org/browse.aspx?flora_id=1

iNaturalist Plant Search https://www.inaturalist.org/home

Plants For A Future on Carduus nutans https://pfaf.org/user/Plant.aspx?LatinName=Carduus+nutans

USDA Plants Database https://plants.sc.egov.usda.gov/home

Willis, Lyrae (2022). Plant Families of North America. Not yet published.

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22 Aug, 2022

17 Jun, 2022

Gossypium hirsutum Mexican Cotton - Native Species of the Week

Gossypium hirsutum leaf and fruit in the evening sun Sinaloa, Mazatlan, Mexico — *Gossypium hirsutum* leaf and fruit in the evening sun Sinaloa, Mazatlan, Mexico

Mexican Upland Cotton Gossypium hirsutum – Native Plant of the Week
Introduction
Description of Upland Cotton Gossypium hirsutum
Similar Species Frequently Confused With
Distribution of Upland Cotton Gossypium hirsutum
Habitat & Growing Conditions of Mexican Cotton Gossypium hirsutum
Growing Mexican Cotton in Your Garden
Wildlife Values of Gossypium hirsutum
Status of Gossypium hirsutum
Traditional or Other Uses of Upland Cotton
Ethical Wildcrafting of Gossypium hirsutum
References and Resources

Mexican Upland Cotton Gossypium hirsutum – Native Plant of the Week

Introduction

Gossypium hirsutum has large and beautiful pale-yellow flowers and seeds covered in white cotton. It is both a beautiful and useful plant. The flowers are typical Malvaceae-type flowers with large overlapping petals and a staminal column in the center. It is native to Mexico and possibly southern Florida as well as the West Indies, Central America and northern South America. While it grows throughout the southern USA it is not native in most of it. Mexico is considered to be the center of origin and genetic diversity for Gossypium hirsutum where it was domesticated at least as far back as 3500 BC according to archeological evidence. This species of cotton accounts for about 90% of the worldwide cotton production and about 95% of the cotton production in the Americas.