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Asimina Adans.

Pawpaw

Synonyms
  • Deeringothamnus Small
  • Orchidocarpum Michx.
  • Pityothamnus Small
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Treatment and Overview

Asimina Adans. (pawpaw) comprises 12 accepted living species of deciduous shrubs and small trees in the Custard-apple Family (Annonaceae), together with seven named natural hybrids recognized by Tree TSAR. Pawpaws are native to eastern and south-central North America, with their center of diversity in the southeastern United States and especially Florida. The best-known species, Asimina triloba (Northern pawpaw), is a temperate understory tree cultivated for its unusually large edible fruits. Most of its relatives are smaller shrubs of southern pine flatwoods, sandhills, scrub, and other Coastal Plain habitats. All species are woody trees or shrubs.

Tree TSAR’s count of 12 species differs from the current Plants of the World Online treatment, which recognizes 11 because it includes A. spatulata within A. angustifolia. Tree TSAR follows modern southeastern floristic treatments in recognizing A. spatulata, the spoonleaf pawpaw, as a distinct species. (Ward, 2001; Weakley, 2023; Franck, 2026).

Pawpaws generally have simple, alternate, entire leaves and solitary or few-flowered inflorescences. Their flowers retain the characteristic three-parted organization of Annonaceae, usually with three sepals and six petals, although floral size, color, fragrance, petal differentiation, and stamen number vary markedly among species. The fruits consist of fleshy berries developing from separate carpels, often with several fruits arising from a single flower. Floral colors range from white, cream, and yellow to pink, red, and deep maroon. These differences are accompanied by considerable variation in scent chemistry and pollination biology. (Kral, 1960; Goodrich & Raguso, 2009).

The name pawpaw is sometimes confused with papaya because “pawpaw” or “papaw” is also applied to Carica papaya in parts of the English-speaking world. The two are only very distantly related: Asimina belongs to Annonaceae in Magnoliales, whereas papaya belongs to Caricaceae in Brassicales.

Asimina and Deeringothamnus

The boundaries of Asimina were debated for much of the twentieth century. John K. Small separated the diminutive Florida species now known as Asimina pulchella and A. rugelii into the genus Deeringothamnus, emphasizing their unusual floral morphology. Compared with many other pawpaws, they have relatively small flowers, flatter receptacles, fewer stamens, and petals that are less strongly differentiated into inner and outer whorls. Kral’s influential 1960 revision likewise maintained Asimina and Deeringothamnus separately. (Kral, 1960).

The distinction was never entirely clear-cut. Morphological and biochemical differences suggested fuzzy boundaries, if any, between the putative genera while evidence of natural hybridization showed that the supposed generic boundary did not correspond to reproductive isolation. Norman (2003) reported putative natural hybrids between A. pygmaea and the former Deeringothamnus rugelii, and between A. reticulata and the former D. pulchellus. Later work combining ISSR molecular markers, morphology, and floral-scent chemistry found Deeringothamnus embedded within Asimina in the molecular analysis rather than forming an independent sister genus. (Norman, 2003; Mercer et al., 2016). Therefore, the evidence strongly supports treating Deeringothamnus as a synonym of Asimina.

Maas et al. (2011) had already incorporated the former Deeringothamnus species into Asimina in their updated Annonaceae index. Much stronger nuclear evidence now reinforces that treatment. Fonseca et al. (2024), using hundreds of nuclear loci, recovered the combined Asimina–Deeringothamnus lineage as monophyletic in every analysis. The two traditional Deeringothamnus species also formed a strongly supported group in the preferred supercontig analysis. Internal branching varied among datasets, however, and the authors identified incomplete lineage sorting and introgression as possible contributors to the difficult species-level phylogenetic signal. The modern evidence therefore strongly supports including Deeringothamnus within Asimina without implying that every species relationship among the pawpaws is completely resolved.

Current global databases are increasingly consistent with this interpretation. Plants of the World Online treats Deeringothamnus, Orchidocarpum, and Pityothamnus as synonyms of Asimina.

Relationships and evolutionary history

Within Annonaceae, Asimina belongs to subfamily Annonoideae, tribe Annoneae, and subtribe Annoninae. Its closest living generic relative is the Southeast Asian Disepalum, producing one of the more striking geographic disjunctions in the family. Complete genus-level nuclear phylogenomics supports the position of Asimina within Annoninae and the broader modern classification of the family. (Nge et al., 2024).

The Asimina–Disepalum split is ancient relative to the comparatively young radiation of living pawpaws. Li et al. (2017) estimated the separation of the North American and Asian lineages at approximately 40 million years ago, during the Eocene. This timing coincides broadly with deterioration of the warm boreotropical forests that had once extended across high northern latitudes. Such forests could have provided an ecological connection between North America and Eurasia before cooling toward the Eocene–Oligocene boundary fragmented thermophilic plant distributions.

Living Asimina, by contrast, diversified within North America. Its extraordinary ecological range is visible today in the contrast between A. triloba, which reaches the Great Lakes region and southern Ontario, and the narrowly endemic subtropical shrubs of Florida. The genus therefore represents a predominantly southeastern North American radiation nested within a lineage whose deeper history once extended much farther across the Northern Hemisphere.

Fossil seeds assigned to Asimina brownii have been reported from Miocene and Pliocene deposits in Europe and resemble seeds of living Asimina. Their occurrence suggests that Asimina or a closely related lineage persisted in European warm-temperate or subtropical vegetation long after the original transcontinental boreotropical connection had begun to fragment. Fossil taxa are not included among the accepted living species.

Species boundaries and hybridization

Species boundaries within Asimina are complicated by relatively modest molecular differentiation, substantial morphological variation, and a demonstrated capacity for hybridization. Seven named natural hybrids are recognized by Tree TSAR, several involving parents assigned to different major phylogenetic clades. Experimental and field evidence indicates that even morphologically distinctive pawpaws can retain considerable cross-compatibility. Geographic separation, habitat specialization, flowering phenology, and pollinator behavior therefore appear to have played important roles in maintaining species boundaries despite incomplete intrinsic reproductive isolation. (Norman, 2003; Mercer et al., 2016; Fonseca et al., 2024).

Asimina manasota represents one relatively recent addition to the accepted flora. Described from west-central Florida, it is now accepted by major contemporary floristic and global treatments. Its extremely restricted distribution in Manatee and Sarasota counties also makes recognition of the taxon particularly consequential for conservation.

Tree TSAR also recognizes A. spatulata separately from the closely related A. angustifolia. The two have a long history of treatment either as separate taxa or within a broader A. longifolia–A. angustifolia complex. Current southeastern floras recognize them at species rank, whereas several global taxonomic databases retain a broader A. angustifolia. Tree TSAR follows the regional species-level treatment while recognizing that targeted population-level molecular study would be valuable for further testing their limits. (Kral, 1960; Ward, 2001; Weakley, 2023; Franck, 2026).

Horticultural and Agricultural Uses

The horticultural and agricultural importance of Asimina is concentrated overwhelmingly in Asimina triloba, the Northern pawpaw. Its large fruits contain soft yellow to orange flesh with an aromatic flavor frequently compared with banana, mango, pineapple, or other tropical fruits despite the tree’s adaptation to a temperate North American climate. Pawpaw has developed a growing niche as a specialty orchard crop, native fruit, landscape tree, and ingredient for processed foods.

Kentucky State University has become the principal institutional center for modern pawpaw development and maintains what it describes as the only full-time pawpaw research program in the world. Its work includes cultivar development, propagation, orchard management, regional variety trials, fruit ripening and storage, genetic diversity, and germplasm conservation. The university also maintains an extensive clonal germplasm repository.

Propagation presents several unusual challenges. Pawpaw seeds are recalcitrant, meaning that they lose viability if allowed to dry. They also possess dormancy that normally requires an extended period of moist chilling followed by warm, moist conditions before germination. Seedlings are useful as rootstocks and for maintaining genetic variation, but named fruit cultivars do not come true from seed and must be propagated clonally. Grafting and budding onto seedling rootstocks are the standard approaches, with chip budding historically among the most successful methods. (Geneve et al., 2003).

The ecology of A. triloba helps explain its behavior in cultivation. Wild populations often occupy rich mesic woods, stream terraces, and floodplains, where plants tolerate considerable shade and may form colonies through root suckering. Greater light is advantageous for fruit production once young trees are established. Commercial expansion has historically been constrained in part by the fruit’s rapid ripening and short postharvest life, making cultivar development, harvest timing, storage, processing, and value-added uses important components of ongoing research.

The southern shrub pawpaws have much less agricultural importance but considerable horticultural and conservation interest. Several produce striking white, cream, yellow, pink, or maroon flowers and are strongly associated with fire-maintained southeastern habitats. Their deep root systems, habitat specialization, and sometimes poor transplantability make them challenging subjects for conventional nursery production. They are particularly valuable in native-plant collections and conservation gardens representing southeastern Coastal Plain ecosystems.

Asimina also has an important ecological role in wildlife horticulture. Pawpaws are larval host plants of the zebra swallowtail (Protographium marcellus). The widespread A. triloba supports the butterfly across much of its northern range, while the southeastern United States offers numerous additional Asimina hosts.

Conservation Issues

Conservation risk is distributed very unevenly across Asimina. The widespread A. triloba occupies a vast portion of eastern North America, but much of the genus’s evolutionary diversity is concentrated in comparatively localized southeastern shrubs. Florida is particularly important. Scrub, sandhill, pine flatwoods, and related open communities support multiple pawpaw species, several with very restricted ranges.

These habitats are vulnerable not only to direct development but also to fire suppression. Many southern pawpaws evolved in landscapes maintained by recurrent burning. When fire is excluded, shrubs and trees can close the understory and alter the light environment in which low-growing pawpaws flower and persist. Appropriate prescribed fire can therefore be a conservation requirement rather than simply a disturbance to be prevented.

Three accepted Tree TSAR species are federally listed as Endangered in the United States: Asimina tetramera, A. pulchella, and A. rugelii. Federal nomenclature retains the latter two under the legally listed names Deeringothamnus pulchellus and D. rugelii, reflecting the taxonomy used when they were listed. Their placement in Asimina by Tree TSAR follows the modern phylogenetic evidence and does not alter their legal protection. A. tetramera remains listed directly under its current accepted name.

Asimina manasota presents another acute conservation problem. It is confined to Manatee and Sarasota counties in Florida and is considered critically imperiled. Its seeds cannot be conserved effectively by conventional dry seed banking, so institutions have begun developing tissue-culture and cryopreservation approaches. Material collected through the Florida Plant Rescue initiative has produced multiple in-vitro germplasm lines maintained through collaboration among conservation institutions.

Hybridization adds an unusual consideration to restoration. Gene flow is clearly a natural component of Asimina evolution and should not automatically be interpreted as a conservation problem. At the same time, transplanting closely related species or genetically distant populations next to very small endangered populations could create opportunities for hybridization that did not previously exist. Provenance, population identity, and local species composition are therefore relevant when designing ex situ collections, augmentations, or reintroductions.

Infrageneric Groups

Tree TSAR uses three informal phylogenetic clades to organize the living species of Asimina. They are not formal subgenera or sections. The framework is based principally on the molecular relationships developed by Li et al. (2017), interpreted alongside the more recent nuclear phylogenomic results of Fonseca et al. (2024). Because the latter study found some topology to be dataset-dependent, the clades provide a useful evolutionary framework without implying that every internal branch has been definitively resolved.

  • Triloba Clade: Contains A. triloba, the geographically widespread northern lineage and the genus’s principal tree-sized temperate species.
  • Pygmaea Clade: Contains seven accepted species in the Tree TSAR treatment and encompasses much of the southeastern dwarf- and shrub-pawpaw radiation, including A. pulchella and A. rugelii, formerly segregated as Deeringothamnus. A. spatulata is placed here provisionally based on its close relationship to A. angustifolia.
  • Parviflora Clade: Contains four accepted species and represents the other principal southeastern lineage recognized by Tree TSAR.

The Interclade Hybrids category used in the Accepted Taxa table is a practical organizational category rather than a phylogenetic clade. It identifies named hybrids whose parents belong to different Tree TSAR clades, making the extent of reticulation within Asimina visible without implying that the hybrids share a single evolutionary origin.

Accepted Taxa
Asimina angustifolia Raf. Slimleaf pawpaw
Asimina × bethanyensis DeLaney Bethany pawpaw
Asimina × colorata DeLaney Two-tone pawpaw
Asimina incana (W.Bartram) Exell Woolly pawpaw
Asimina × kralii DeLaney Kral pawpaw
Asimina manasota DeLaney Manasota pawpaw
Asimina × nashii Kral Nash pawpaw
Asimina × oboreticulata DeLaney Flag pawpaw
Asimina obovata (Willd.) Nash Bigflower pawpaw
Asimina parviflora (Michx.) Dunal Smallflower pawpaw
Asimina × peninsularis DeLaney Sarasota pawpaw
Asimina × piedmontana C.N.Horn Piedmont pawpaw
Asimina pulchella (Small) Rehder & Dayton Royal pawpaw
Asimina pygmaea (W.Bartram) Dunal Dwarf pawpaw
Asimina reticulata Shuttlew. ex Chapm. Netted pawpaw
Asimina rugelii B.L.Rob. Rugel pawpaw
Asimina spatulata (Kral) D.B.Ward Spoonleaf pawpaw
Asimina tetramera Small Four-petal pawpaw
Asimina triloba (L.) Dunal Northern pawpaw

Additional Information

  • iNaturalist: Asimina taxon page — observations, photographs, identifications, and distributional data.
  • Trees and Shrubs Online: Asimina — horticultural account with particular emphasis on A. triloba.
  • Royal Botanic Gardens, Kew — Plants of the World Online: Asimina Adans. — current global nomenclatural and distribution backbone. POWO recognizes 11 species and seven named hybrids but treats A. spatulata within A. angustifolia.
  • Flora of North America: Asimina — detailed regional morphology and identification keys. The treatment predates modern molecular work and retains Deeringothamnus as a separate genus.
  • Flora of Florida: Current flora — regional treatment for the principal center of Asimina diversity, including recognition of A. spatulata.
  • Kentucky State University Pawpaw Program: Pawpaw Program — extensive information on A. triloba breeding, propagation, cultivars, germplasm conservation, orchard production, and postharvest research.

References and Further Reading

Fonseca, L. H. M., Asselman, P., Goodrich, K. R., Nge, F. J., Soulé, V., Mercier, K., Couvreur, T. L. P., & Chatrou, L. W. (2024). Truly the best of both worlds: Merging lineage-specific and universal probe kits to maximize phylogenomic inference. Applications in Plant Sciences 12(6): e11615. DOI: 10.1002/aps3.11615.

Franck, A. R. (2026). Flora of Florida. University of Florida Herbarium, Florida Museum of Natural History. Flora of Florida

Geneve, R. L., Pomper, K. W., Kester, S. T., Egilla, J. N., Finneseth, C. L. H., Crabtree, S. B., & Layne, D. R. (2003). Propagation of pawpaw: A review. HortTechnology 13(3): 428–433. DOI: 10.21273/HORTTECH.13.3.0428.

Goodrich, K. R., & Raguso, R. A. (2009). The olfactory component of floral display in Asimina and Deeringothamnus (Annonaceae). New Phytologist 183: 457–469. DOI: 10.1111/j.1469-8137.2009.02868.x.

Kral, R. (1960). A revision of Asimina and Deeringothamnus (Annonaceae). Brittonia 12: 233–278. DOI: 10.2307/2805119.

Li, P.-S., Thomas, D. C., & Saunders, R. M. K. (2017). Historical biogeography and ecological niche modelling of the Asimina–Disepalum clade (Annonaceae): Role of ecological differentiation in Neotropical-Asian disjunctions and diversification in Asia. BMC Evolutionary Biology 17: 188. DOI: 10.1186/s12862-017-1038-4.

Maas, P. J. M., Westra, L. Y. T., Rainer, H., Lobão, A. Q., & Erkens, R. H. J. (2011). An updated index to genera, species, and infraspecific taxa of Neotropical Annonaceae. Nordic Journal of Botany 29: 257–356. DOI: 10.1111/j.1756-1051.2011.01092.x.

Mercer, E., Griffin, B., Steele, J., Goodrich, K. R., & Bush, C. M. (2016). Phylogenetic relationships of Asimina and Deeringothamnus (Annonaceae) based on morphology, floral scent chemistry, and Inter-Simple Sequence Repeat data. Journal of the Torrey Botanical Society 143(1): 58–68. DOI: 10.3159/TORREY-D-14-00045.1.

Nge, F. J., Chaowasku, T., Damthongdee, A., et al. (2024). Complete genus-level phylogenomics and new subtribal classification of the pantropical plant family Annonaceae. Taxon 73: 1341–1369. DOI: 10.1002/tax.13260.

Norman, E. M. (2003). Reproductive biology of Deeringothamnus rugelii and D. pulchellus (Annonaceae). Taxon 52: 547–555. DOI: 10.2307/3647453.

Ward, D. B. (2001). New combinations in the Florida flora II. Novon 11(3): 360–365. DOI: 10.2307/3393047.

Weakley, A. S. (2023). Flora of the Southeastern United States. University of North Carolina Herbarium, North Carolina Botanical Garden. Flora of the Southeastern United States

Royal Botanic Gardens, Kew. (2026). Asimina Adans. Plants of the World Online. Asimina

Kentucky State University. (2026). Pawpaw Research Program. School of Agriculture and Natural Resources. Pawpaw Program