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.

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:

1. 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.
2. 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.
3. 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.
4. 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.