Asimina in Flora of North America @ efloras.org

2. Asimina Adanson, Fam. Pl. 2: 365. 1763.

Pawpaw [American Indian assimin through French asiminier ]

Orchidocarpum Michaux; Pityothamnus Small; Porcelia Persoon 1807, not Ruiz & Pavón 1794; Uvaria Torrey & A. Gray

Shrubs or small trees , taprooted; trunks straight in arborescent forms. Bark thin, cracking longitudinally (shallowly furrowed in larger trees of Asimina triloba ). Shoots: secondary branching sparse to copious, 2-ranked; primary shoots of shrubs usually several, erect to arching or decumbent; lenticels scattered, small, prominent; buds naked. Leaves deciduous. Leaf blade membranous or leathery, glabrous to variously hairy. Inflorescences axillary, on new shoots or from above leaf scars of previous seasons, fascicles; peduncle bracteate or bracteolate. Flowers 1-4 per leaf axil, nodding to nearly erect, becoming enlarged; receptacle convex to ±globose or elongate, elevated; sepals deciduous, 3(-4), nearly distinct, triangular to deltate-ovate, valvate in bud; petals in 2 unequal whorls, each of 3-4 equal members, with prominent veins, imbricate in bud, those of outer whorl larger, thinner than those of inner whorl; nectaries present, usually with differently pigmented, thickened-corrugate zones adaxially near petal bases; stamens very numerous, short-columnar, forming ball; filament short; connective blunt to nearly spheric or cuboid; pistils 2-8(-12), sessile to stipitate, distinct, glabrate; ovules several (sometimes few) in 2 staggered rows. Fruits simple berries, usually 3-5 per flower, spreading from swollen receptacles, unevenly oblong-cylindric, pulpy. Seeds 3-many per pistil, bean-shaped, slightly compressed laterally, coat tough, margins absent. x =9.

Species 8 (8 in the flora): subtropical and temperate North America.

SELECTED REFERENCES

Exell, A. W. 1927. William Bartram and the genus Asimina in North America. J. Bot. 65: 65-70. Nash, G. V. 1896. Revision of the genus Asimina in North America. Bull. Torrey Bot. Club 23: 234-242. Uphof, J. C. T. 1933. Die nordamerikanischen Arten der Gattung Asimina. Mitt. Deutsch. Dendrol. Ges. 45: 61-76. Wilbur, R. L. 1970. Taxonomic and nomenclatural observations on the eastern North American genus Asimina (Annonaceae). J. Elisha Mitchell Sci. Soc. 86(2): 88-96. Zimmerman, G. A. 1941. Hybrids of the American pawpaw. J. Heredity 32: 82-91.

1 Leaf blade commonly membranous, oblong-obovate to oblanceolate, apex acute to acuminate; flowers maroon, rarely yellow, fetid, from previous year's shoots before or during new leaf emergence; inner petals with saccate base. (2)

+ Leaf blade commonly leathery, linear to obovate, apex acute to broadly rounded or notched; flowers white or yellow-white to red or maroon, fetid or sweet-smelling, from previous year's growth or from new shoots. (3)

2 (1) Flowers 2-4(-5) cm diam.; peduncle 1 cm or more at anthesis, hairs dark brown to red-brown; corrugate zone of inner petals distinct. 1 Asimina triloba

+ Flowers 1-1.7 cm diam.; peduncle less than 1 cm at anthesis, hairs red-brown to tan; corrugate zone of inner petals indistinct or absent. 2 Asimina parviflora

3 (1) Flowers from nodes of previous year's growth, emerging before or with leaves; leaf blade elliptic or oblong, obovate or cuneate, never linear, lance-linear, or oblanceolate; flowers large, sweetly fragrant. (4)

+ Flowers from shoots of current year's growth, emerging after leaves are expanding or full-size, either axillary to new leaves or terminal on short shoots; leaf blade linear to narrowly obovate or spatulate; flowers large to small, fragrant or fetid. (5)

4 (3) Abaxial and adaxial surfaces of young leaf blade densely tomentose, hairs pale blond or tan; fully emerged leaf blade oblong to obovate, margins obscurely revolute, inner petals yellow-white with deep yellow corrugate nectary zone. 3 Asimina incana

+ Abaxial surface of young leaf blade densely orange-hairy, adaxial surface sparsely orange-hairy; fully emerged leaf blade narrowly obovate to oblong or elliptic, margins strongly to moderately revolute; inner petals white or yellowish white, rarely pink or cherry red, mostly with deep maroon to purple corrugate zone. 4 Asimina reticulata

5 (3) New shoots, petiole, abaxial surface of leaf blade along veins, and peduncle with dense, bright red hairs; new growth with flowers (buds) terminal. 5 Asimina obovata

+ New shoots, petiole, abaxial surface of leaf blade, and peduncle glabrous to sparsely hairy; new growth with flowers axillary to new leaves. (6)

6 (5) Mature shrubs seldom more than 0.5m, shoots decumbent to arching; perianth maroon to red, outer petals 1.5-3 cm. 6 Asimina pygmaea

+ Mature shrubs seldom less than 1m, shoots erect to nearly erect; perianth white to red or maroon, outer petals 2-8 cm. (7)

7 (6) Leaf blade oblong-oblanceolate to broadly spatulate; expanded flowers reddish, fetid; outer petals 2-2.5 cm; perianth 3-4-merous; Florida. 7 Asimina tetramera

+ Leaf blade linear, linear-elliptic, linear-oblanceolate, or narrowly spatulate; expanded flowers mostly with outer petals white or cream and inner petals red or white, sweet-smelling; outer petals 3-8 cm; perianth mostly 3-merous; nFlorida, Georgia, Alabama. 8 Asimina longifolia

Lower Taxa