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.  

Beginner’s Guide to the Custard Apple (Annonaceae) Family

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 of the Custard Apple Family

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. Leaves never have tiny appendages at their base called stipules, which helps distinguish them from the Magnoliaceae.

Flowers of the Custard Apple Family

The flowers are arranged singly or in branched clusters. They 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 2 inner layers of petals that are often thick and fleshy and sometimes contain visible nectar glands.

Reproductive Features of the Custard Apple Family

The male parts are very distinct, usually with many stamens that are packed together in a characteristic dense ball or flat-topped mass in the center of the flower, which is a good character to help identify the family. The ovary is superior, sitting above the point of where the petals attach.

Fruits of the Custard Apple Family

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 encased in brightly colored fleshy coatings (aril or sarcotesta) that attract birds and animals.

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 for more information on Asimina triloba

Uses of Annonaceae 

Many have edible fruits, but non-commercial varieties should be eaten with caution, as they contain varying levels of annonacin, which has been implicated in neurodegenerative diseases. Still, 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.

Ecosystem and Wildlife Values of Annonaceae 

The Annonaceae family provides critical, large, nutrient-rich aggregate fruits that serve as major food resources for tropical frugivores like primates, bats, toucans, tapirs, and peccaries, while in temperate zones, Asimina triloba fruits feed raccoons, foxes, opossums, and black bears.

Many species have fleshy flowers that smell of rotting meat, relying on beetles and small flies for pollination, who are rewarded with food or brood sites, while they also serve as host plants for many Lepidoptera, particularly swallowtail butterflies, that rely on the leaves for food.

In tropical forests, especially in Africa and the neotropics, Annonaceae species are critical parts of the forest structure, often dominating the understory.

Taxonomy of Annonaceae

The Annonaceae family has between 2,400 and 2,500 species in 107-110 genera, depending on the classification. They are part of the Magnoliales order in the Magnoliids clade, which is an early-diverging lineage of mesangiosperms, not a true dicot or monocot.

The family is divided into 4 subfamilies as follows:

Anaxagoreoideae Subfamily

The Anaxagoreoideae is a group of 25 species in a single genus found in tropical America and the tropics in Southeast Asia. They have 2-ranked trunk leaves, sessile stigmas, and dry follicles that are explosively dehiscent, which is a key diagnostic feature.

Genera of the Anaxagoreoideae Subfamily

Anaxagorea (25).

Ambavioideae Subfamily

The Ambavioideae is a more widespread group found throughout the tropics and subtropics. 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.

Genera of the Ambavioideae Subfamily

Ambavia (2), Cananga (2), Cleistopholis (4), Cyathocalyx (7-12), Drepananthus (28), Lettowianthus (1), Mezzettia (5), and Tetrameranthus (8).

Annonoideae Subfamily

The Annonoideae is a widespread but mostly tropical subfamily, but it does extend into temperate eastern North America. It is characterized by trimerous whorls, often highly modified stamens, and specialized aggregate fruits.

Genera of the Annonoideae Subfamily

Afroguatteria (3), Annona (171), Anonidium (5), Artabotrys (111), Asimina (11), Asteranthe (2), Bocagea (4), Cardiopetalum (3), Cleistochlamys (1), Cymbopetalum (27), Dasymaschalon (31), Desmos (19), Diclinanona (3), Dielsiothamnus (1), Disepalum (10), Duckeanthus (1), Duguetia (97), Fissistigma (59), Friesodielsia (53), Froesiodendron (3), Fusaea (2), Goniothalamus (139), Guatteria (175+), 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 Subfamily

The Malmeoideae is restricted to the lowland tropics and is characterized by pollen with a single aperture and specific molecular markers, as well as often having a glass-like endosperm with spiniform ruminations.

Genera of the Malmeoideae Subfamily

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

Because the Annonaceae share primitive morphological traits with other orders in the Magnoliid clade (such as alternate, entire leaves, aromatic tissues, trimerous flowers, and multiple stamens), field identification can sometimes be tricky.

Myristicaceae members can look similar, but they are easily distinguished by their clear to blood-red latex, which is visible when the bark is slashed. Plants are also dioecious with small, apetalous flowers compared to usually bisexual Annonaceae flowers with distinct sepals and petals.

Magnoliaceae can be differentiated by their large deciduous stipules that leave a distinct ring-like scar surrounding each node, while the Annonaceae have no stipules at all. Magnoliaceae also produce aggregates of follicles or samaras with seeds hanging via funicles, while Annonaceae form berries or syncarps.  

The Lauraceae family also shares simple, aromatic leaves and woody habits, but the Lauraceae anthers open via characteristic upward-curving valves or flaps, whereas Annonaceae anthers open via longitudinal slits. The Lauraceae also produce flowers with a single carpel that produces single-seeded drupes, often accompanied by a receptacle or cupule, rather than aggregate berries or syncarps.

Scientific Botanical Description of the Annonaceae

Habit & Leaf Form of the Annonaceae

The Annonaceae are always 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 via scrambling or hooked, woody pedicels.

Leaves are typically arranged alternately in a spiral and are non-sheathing, simple, and petiolate and may or may not be gland-dotted or aromatic. The lamina and its margins are entire, and the lamina is always pinnately veined and cross-venulate. Leaves have no stipules. Domatia occurs in 10+ genera as pockets or occasionally as hair tufts.

Flowers of the Annonaceae

Annonaceae plants are usually hermaphrodite or sometimes dioecious and rarely monoecious. They are often axillary but may be terminal, leaf-opposed, or cauliflorous. They are typically in monochasial cymes but may be reduced to a solitary flower or in fasciculate clusters.

The receptacle may be elevated, enlarged, or flat. Flowers are regular and cyclic or partially acyclic. Free hypanthium is absent, and a hypogynous disk is present.

The flowers are strictly 3-merous, arranged in 3 distinct whorls, with 3 parts in each whorl (9 parts, rarely more). The perianth has a distinct calyx and corolla that may be petaline; however, sometimes it can be difficult to determine when the outer 1-2 whorls are sepaloid.

The calyx has 3 parts, typically free (sometimes basally connate), and the lobes are longer than the tube but smaller and thinner than the petals.

The corolla typically has 6 free parts (sometimes basally connate) in 2 distinct whorls. Petals are usually thick, fleshy, or coriaceous, with valvate or imbricate aestivation. Inner petals may be smaller, clawed, or connivent over the reproductive organs and frequently bear nectar-secreting glands at their bases. Rarely is the inner petal whorl missing.  

Androecium of the Annonaceae

The androecium contains 6–100+ members that mature centripetally. Members are usually fertile stamens, but sterile staminodes occur in several lineages and are usually located outside or inside the fertile stamens; staminodes are non-petaloid and are often reduced, glandular, or shield-like.

Stamens are free of the perianth and each other, are all equal, and are usually densely packed and spirally arranged in multiple whorls on the receptacle, often forming a compact protective ball or flat-topped shield around the gynoecium.

Filaments are characteristically short, stout, and thick. Anthers are adnate, non-versatile, linear to oblong, tetrasporangiate, and extrorse and dehisce via longitudinal slits away from the gynoecium.

Gynoecium of the Annonaceae

The gynoecium is superior and contains 1 (rare) to 100+ carpels. It is usually apocarpous (carpels spiraled or cyclic) or synstylovarious to syncarpous (e.g., Monodora).

The carpel contains one to many ovules. Placentation in apocarpous taxa of individual carpels is ventral or basal when reduced to a single ovule; free carpels are basal. When syncarpous, placentation is parietal.

Stigmas are of the wet type and papillate, secreting a sticky, mucilaginous exudate. In many apocarpous species, individual stigmas coalesce into an aggregate head.

Ovules are anatropous, bitegmic, and crassinucellate. They are ascending with a ventral raphe and may be arillate at the base, developing a distinct sarcotesta or aril.  

Fruit of the Annonaceae

The fruit of the Annonaceae is a fleshy aggregate that is often made of berries; sometimes fruiting carpels coalesce into a secondary syncarp. The fruiting carpel is indehiscent or pseudo-dehiscent.

Seeds are endospermic with 1 to many per pistil and may be encased in fleshy white, yellow, orange, or red arils or sarcotesta, which attract frugivorous birds and animals. The endosperm is ruminate, oily, and has amyloid.

Global Distribution of Annonaceae

The Annonaceae are primarily a subtropical and tropical family, especially common in lowland forests, and are very rarely temperate. It is widespread, especially in the Old World. In the Americas, it is found all over the Neotropics and north as far as southern Canada.  

Distribution of Annonaceae in the Americas

Canada Annonaceae Genera

Annonoideae Subfamily in Canada

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

USA Annonaceae Genera

Annonoideae Subfamily in the USA

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 Annonaceae Genera

Anaxagoreoideae Subfamily in Mexico

Anaxagorea 1 sp. native to SW Mexico, Ver.

Ambavioideae Subfamily in Mexico

Cananga 1 sp. intro to SW Mexico, Ver.

Annonoideae Subfamily in Mexico

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 Subfamily in Mexico

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 Annonaceae Genera

Anaxagoreoideae Subfamily in the Neotropics

Anaxagorea ~22 spp. native to 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 Subfamily in the Neotropics

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 Subfamily in the Neotropics

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 Subfamily in the Neotropics

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 Annonaceae 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.
• 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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