How to Identify the Annonaceae or Custard Apple Family

5 Sep, 2022

How to Identify the Annonaceae or Custard Apple Family

Asimina triloba - a temperate species of Annonaceae found as far north as southern Canada. Photo from Hampton, VA, USA by Lyrae Willis
Asimina triloba – a temperate species of Annonaceae found as far north as southern Canada. Photo from Hampton, VA, USA by Lyrae Willis

Table of contents

Introduction to the Annonaceae Family

The Annonaceae is an interesting family of trees and shrubs with unique flowers and fleshy, often edible 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. The flowers shown in the photo above of Asimina triloba 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.  Sometimes 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.  

Flowers of the Annonaceae

Plants are usually hermaphrodite or sometimes dioecious and rarely monoecious. The flowers are usually trimerous. 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, but it can be hard to determine when the outer 1-2 whorls are sepaloid. Perianth has 9 (10–12) parts, maybe basally joined or free, is usually 3 whorled, isomerous, and may be similar or different in the whorls. Calyx has 3 or 6 parts, typically 2 whorled, free (sometimes basally connate), and the lobes are longer than the tube. Corolla has 3 or 6 parts, is 1–2 whorled, 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, usually spiraled, and 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 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

Gynoecium is 10–100(+) carpelled. When syncarpous, the pistil is 1 or 2–15+ celled.  It is usually apocarpous (carpels spiraled or cyclic) or synstylovarious to syncarpous (e.g. Monodora); the ovary is superior. Carpel is 1–10 ovuled. Placentation of free carpels is basal. Ovary when syncarpous is 1 or 2–15+ locular. Stigmas are wet type and papillate, Group III type. Placentation when unilocular is parietal or basal, when plurilocular it is basal. Ovules in the single cavity when unilocular is 1–50 with 10–50 per locule. Ovules are ascending, apotropous, have a ventral raphe, may be arillate or not, 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 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 may be deciduous or evergreen and produce essential oils and may or may not be resinous.  The bark is fibrous and aromatic and pith septate to diaphragmed. Plants may be self-supporting or climbing. When climbing, they are scrambling or stem or petiole twiners. Branching is distichous or spiral.  Leaves are persistent, alternate, non-sheathing, simple, petiolate, and may or may not be gland-dotted or aromatic. Lamina is entire, pinnately veined (sometimes palmately), and is cross-venulate. Leaves are exstipulate. Lamina margins are entire. Domatia occur in 3 genera as pockets or occasionally as hair tufts.

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 commercial fruits come from Annona spp (atemoya, cherimoya, custard-apple, ilarma, sugar-apple, sweet sop, soursop) and Artabotrys. Medicinal uses include as an analgesic and astringent and to treat various conditions, including snakebite, diarrhea, dysentery, arthritis pain, rheumatism, convulsion, neuralgia, and weight loss.

Morphology of Annonaceae in North America

So far in North America, I have only photographed Asimina triloba, but here are some pictures of different morphological aspects of that species.

Androecium & Gynoecium of Asimina triloba showing a ball that the short, stout filaments of the stamens typically form in Annonaceae species
Androecium & Gynoecium of Asimina triloba showing a ball that the short, stout filaments of the stamens typically form in Annonaceae species
Young Floral Bud of Asimina triloba - shows 2 of the 3 parts of the calyx typical of Annonaceae species (the other sepal is on other side out of view).
Young Floral Bud of Asimina triloba – shows 2 of the 3 parts of the calyx typical of Annonaceae species (the other sepal is on other side, out of view).
Sepals of Asimina triloba - shows the 3 sepals of the calyx that is typical of the Annonaceae family.
Sepals of Asimina triloba – shows the 3 sepals of the calyx that is typical of the Annonaceae family.
Leave of Asimina triloba - simple, petiolate leaves like these are typical of Annonaceae species.
Leave of Asimina triloba – simple, petiolate leaves like these are typical of Annonaceae species.
Bark & Buds of Asimina triloba - fibrous bark is typical of the Annonaceae.
Bark & Buds of Asimina triloba – fibrous bark is typical of the Annonaceae.
Young Tree of Asimina triloba - trees are common among the Annonaceae.
Young Tree of Asimina triloba – trees are common among the Annonaceae.

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 of the Annonaceae family

Asimina triloba – American Pawpaw

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, borne singly on stout hairy axillary peduncles, appearing with or before the leaves in spring. Fruit is a large yellowish to brown berry 5 – 15 cm long and 20 – 510g that is edible and sweet. Native to eastern North America. Click here to read my blog on this species

Taxonomy of Annonaceae

The Annonaceae family has approx 2300 species in 111 genera of the Magnoliales Order in the Magnoliids Clade of Peripheral (Non-dicot or monocot) Angiosperms.   

Genera:

Afroguatteria (2), Alphonsea (36), Ambavia (2), Anaxagorea (25), Annickia (11), Annona (171 inc Raimondia, Rollinia, Rolliniopsis), Anonidium (4), Artabotrys (108), Asimina (9), Asteranthe (2), Balonga (1), Bocagea (2), Bocageopsis (4), Boutiquea (1), Brieya (2), Cananga (4), Cardiopetalum (3), Chieniodendron (1), Cleistochlamys (1), Cleistopholis (3), Cremastosperma (31), Cyathocalyx (9), Cymbopetalum (27), Dasymaschalon (27), Deeringothamnus (1), Dendrokingstonia (3), Desmopsis (23), Desmos (18), Diclinanona (3), Dielsiothamnus (1), Disepalum (9), Drepananthus (27), Duckeanthus (1), Duguetia (95 inc Pachypodanthium), Ephedranthus (7), Fenerivia (5), Fissistigma (58), Friesodielsia (38 inc Schefferomitra), Froesiodendron (3), Fusaea (3),  Goniothalamus (134 inc Richella), Greenwayodendron (6), Guatteria (184 inc Guatteriella, Guatteriopsis, Heteropetalum), Hexalobus (5), Hornschuchia (10), Huberantha (34), Isolona (20), Klarobelia (13), Leoheo (1), Letestudoxa (3), Lettowianthus (1), Maasia (6), Malmea (6), Marsypopetalum (5), Meiocarpidium (1), Meiogyne (32 inc Ancana, Fitzalania, Guamia, Oncodostigma, Polyaulax), Mezzettia (4), Miliusa (59), Mischogyne (5), Mitrella (8), Mitrephora (49), Mkilua (1), Monanthotaxis (77 inc Exellia, Gilbertiella), Monocarpia (4), Monocyclanthus (1), Monodora (15), Monoon (72 inc Enicosanthum, Woodiellantha), Mosannona (14), Mwasumbia (1), Neo-uvaria (7), Neostenanthera (5), Onychopetalum (2), Ophrypetalum (1), Orophea (60 inc Mezzettiopsis), Oxandra (28), Phaeanthus (8), Phoenicanthus (2), Piptostigma (13), Platymitra (2), Polyalthia (92 inc Haplostichanthus, Papualthia), Polyalthiopsis (1), Polyceratocarpus (10), Popowia (32), Porcelia (7), Pseudartabotrys (1), Pseudephedranthus (2), Pseudomalmea (4), Pseudoxandra (24), Pseuduvaria (58 inc Craibella, Oreomitra, Petalolophus), Pyramidanthe (1), Ruizodendron (1), Sageraea (9), Sanrafaelia (1), Sapranthus (7), Sirdavidia (1), Sphaerocoryne (7), Stelechocarpus (3), Stenanona (16 inc Reedrollinsia), Tetrameranthus (8), Toussaintia (4), Tridimeris (2), Trigynaea (9), Trivalvaria (8), Unonopsis (48), Uvaria (168 inc Anomianthus, Cyathostemma, Dasoclema, Ellipeia, Ellipeiopsis, Melodorum, Tetrapetalum), Uvariastrum (5), Uvariodendron (15), Uvariopsis (18 inc Dennettia, Tetrastemma), Wangia (2), Wuodendron (1), Xylopia (109 inc Pseudannona, Unona).

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:

Asimina 1 of 9 E NAM endemic spp native ON.    

USA Genera:

Annona 3 of 171 Americas + Africa spp native FL; Artabotrys 1 of 108 Old World Tropics spp intro HI; Asimina 9 of 9 E NAM endemic spp native E USA from ND S to TX and all states E exc ND, SD, MN, CT, RI, VT, NH, ME, inc 8 spp endemic to E USA; Deeringothamnus monospecific endemic of FL; Polyalthia 1 of 92 Australasian spp intro FL. 

Mexico Genera:

Anaxagorea 1 of 25 Americas + tropical Asia spp native SW mexico, Ver; Annona (inc Rollinia) 14 of 171 Americas + Africa spp inc 12 native all through Mexico and 1 sp intro Sin E to Tam and S to Oax, Chp, QR, Yuc; Cananga 1 of 2 tropical Asia spp intro SW Mexico, Ver; Cymbopetalum 2 of 27 Mexico + Neo endemic spp native Chp, Ver, Oax?; Desmopsis 8 of 23 Mexico + N Neo endemic spp native Gro, Mic, Chp, Oax, Ver inc 6 narrow endemics of Ver (2), Mic (1), Gro (1), Oax + Ver (2); Guatteria 2 ?? of 184 Neo endemic spp spp native SW+SE+S Mexico, Ver; Mosannona 1 of 14 Mexico + Neo endemic spp native Cam, Chp, QR, Ver, Yuc; Oxandra 4 of 28 Mexico + Neo endemic spp native SW+C+SE Mexico, Ver, inc 1 narrow endemic of Chp; Sapranthus 3 of 7 Mexico + Neo endemic spp native Gro, Oax, QR, Sin, Chp, Ver, inc 1 narrow endemic of Chp; Stenanona 8 of 16 Mexico + N Neo endemic spp native rainforests of SW+SE Mexico, Ver inc 7 narrow endemics of Chp (3), Ver + Oax (2), Tab + Chp (1), Ver + Oax + Chp (1); Tridimeris 2 of 2 Mexican endemic spp native E+C Mexico inc 1 narrow endemic of Chp; Unonopsis ?? of 48 Neo endemic spp native SW+SE Mexico; Uvaria 1 of 168 Old World Tropics spp intro Jal; Xylopia 1 of 169 pantropical spp native S Chi.

Neotropical Genera:

Anaxagorea 22 of 25 Americas + tropical Asia spp native CAM (exc El Salvador), Trinidad-Tobago, tropical SAM S to Peru, Bolivia, C+SE Brazil, inc 5 narrow endemics of Costa Rica & Panama (1), S Venezuela (2), N Peru (1), SE Brazil (1); Annona ?? of 171 spp mostly Americas and some tropical Africa spp native and widely distributed and cultivated for fruit, throughout CAM, Bahamas, Antilles, SW Caribbean, tropical SAM S to N Argentina (exc N Chile); Bocagea 2 of 2 spp endemic to E Brazil; Bocageopsis 4 of 4 SAM endemic spp native Colombia, Venezuela, Guyana, Suriname, French Guiana, N+C+S Brazil, Peru, Bolivia; Cananga 1 of 2 tropical Asia spp intro Guatemala, Nicaragua, Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is, Trinidad-Tobago; Cardiopetalum 3 of 3 N SAM endemic spp of Suriname, French Guiana, N+C+E Brazil, Peru, Bolivia; Cremastosperma 34 of 34 Neo endemic spp native Costa Rica, Panama, Colombia, Venezuela, N+C Brazil, Ecuador, Peru, Bolivia, found in lowland or pre-montane forests, most diversity in the narrow tropical zone W of the Andes; Cymbopetalum 27 of 27 Mexico + Neo endemic spp native from S Mexico S through CAM and tropical SAM S to Peru, Bolivia, C+E Brazil; Desmopsis 17 of 23 S Mexico + N Neo endemic spp native CAM, Cuba, Colombia; Desmos 1 of 18 Australasian spp intro C+E Brazil, Trinidad-Tobago; Diclinanona 3 of 3 N SAM endemic spp native N+C Brazil, Colombia, Peru, Venezuela; Duckeanthus monospecific narrow endemic of N Brazil; Duguetia 91 of 95 Neo + Africa spp native Nicaragua S through tropical SAM S to Peru, Bolivia, Paraguay, S Brazil, 4 spp endemic to W Africa; Ephedranthus 7 of 7 SAM endemic spp native tropical SAM S to Peru, Bolivia, Paraguay, SE Brazil (exc Ecuador); Froesiodendron 3 of 3 N SAM endemic spp native Colombia, Peru, N Brazil; Fusaea 3 of 3 N SAM endemic spp native N+NE+C Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, Venezuela, Bolivia; Guatteria 184 of 184 Neo endemic spp native from S Mexico S through CAM (exc El Salvador), Cuba, Hispaniola, Puerto Rico, Leeward & Windward Is, tropical SAM S to Peru, Bolivia, C+S Brazil, a dominant genus in SAM mature forests; Hornschuchia 10 of 10 narrow endemic spp of E Brazil; Klarobelia 13 of 13 Neo endemic spp native from Costa Rica S to Colombia, Venezuela, N Brazil, Ecuador, Peru, Bolivia, inc several endemics to Ecuador; Malmea 6 of 6 Neo endemic spp native Panama, Colombia, Guyana, Suriname, N+NE Brazil, Peru; Monodora 1 of 15 African spp intro Trinidad-Tobago; Monoon 1 of 72 Australasian spp intro Trinidad-Tobago; Mosannona 14 of 14 Mexico + Neo endemic spp native Guatemala, Belize, Honduras, Costa Rica, Panama, Colombia, N Brazil, Guyana, Suriname, Ecuador, Peru, Bolivia, common in rainforests around Andes, inc 6 narrow endemics of Costa Rica (1), Barro Colorado Is Panama (1), Guatemala (1), Suriname + Guyana (1), Ecuador (1); Onychopetalum 2 of 2 Neo endemic spp of Venezuela, N+C Brazil, Peru, Bolivia; Oxandra 28 of 28 Mexico + Neo endemic spp native S Mexico, Guatemala, Belize, Nicaragua, Costa Rica, Panama, Greater Antilles (exc Cayman Is), Leeward + Windward Is, SW Caribbean, tropical SAM S to Peru, Bolivia, C+SE Brazil, inc 9 narrow endemics of Colombia (3), Suriname (1), Guyana (1), Brazil (4); Polyalthia 1 of 92 SE Asia + Australasia spp intro Trinidad-Tobago; Porcelia 7 of 7 Neo endemic spp native Panama, Colombia, Venezuela, N+E+S Brazil, Ecuador, Peru Bolivia; Pseudephedranthus 2 of 2 N SAM endemic spp of Venezuela, Guyana, Suriname, N Brazil; Pseudomalmea 4 of 4 N SAM endemic spp of Colombia, Venezuela, N Brazil, Ecuador, Peru, Bolivia; Pseudoxandra 24 of 24 SAM endemic spp native Colombia, Venezuela, Guyana, French Guiana, N+C Brazil, Peru, Bolivia; Ruizodendron monospecific N SAM endemic of Colombia, N Brazil, Ecuador, Peru, Bolivia; Sapranthus 6 of 7 Mexico + N Neo endemic spp native CAM, Colombia, inc 1 narrow endemic of Cesar Colombia; Stenanona 9 of 16 Mexico + N Neo endemic spp native rainforests of CAM (exc El Salvador), Colombia, inc 6 narrow endemics of Honduras (2), Costa Rica (1), Panama (1), Colombia (2), the rest are all narrow endemics of Mexico; Tetrameranthus 8 of 8 N SAM endemic spp of N Brazil, Colombia, Venezuela, French Guiana, Ecuador, Peru; Trigynaea 9 of 9 N SAM endemic spp native Colombia, Venezuela, Guyana, Suriname, N+E Brazil, Ecuador, Peru, Bolivia; Unonopsis 48 of 48 Neo endemic spp native S Mexico, CAM (exc El Salvador), tropical SAM S to Peru, Bolivia, C+S Brazil; Uvaria 1 of 168 Old World Tropics spp intro Trinidad-Tobago; Xylopia 40 of 169 pantropical spp native CAM, Cuba, Jamaica, Trinidad-Tobago, tropical SAM S to Peru, Bolivia, NE Argentina. 

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. Orchids, Poaceae, and Cyperaceae have additional references.
  • 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, Alma Rosa Gonzalez-Esquinca (2016). La Familia Annonaceae Juss. En Mexico. Lacandonia ano 10, vol 10, num 2:71-82, Diciembre de 2016.
  • Delta: Watson, L., and Dallwitz, M.J. 1992 onwards. 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.
  • The Plant List (2013). Version 1.1. Published on the Internet; http://www.theplantlist.org/ (accessed 2020 to 2021). No longer updated. Use WFO below.
  • USDA, NRCS. 2020. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC 27401-4901 USA; accessed throughout fall of 2020.
  • Wikipedia: The free encyclopedia. (2004, July 22). FL: Wikimedia Foundation, Inc. Retrieved throughout 2019-current, from https://www.wikipedia.org
  • WFO (2022): World Flora Online. Published on the Internet; http://www.worldfloraonline.org. Accessed Spring 2022 – current

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5 Sep, 2022