Asimina triloba

Asimina triloba, the pawpaw, paw paw, paw-paw, or common pawpaw, is a species of Asimina (the pawpaw genus) in the same plant family (the Annonaceae) as the custard-apple, cherimoya, sweetsop, ylang-ylang and soursop. The pawpaw is native to the Eastern, Southern, and Midwestern United States and adjacent southernmost Ontario, Canada, from New York west to southeastern Nebraska, and south to northern Florida and eastern Texas. The pawpaw is a patch-forming (clonal) understory tree found in well-drained, deep, fertile bottom-land and hilly upland habitat, with large, simple leaves and large fruits. The paw paw is the largest edible fruit indigenous to the United States.

Asimina triloba is a large shrub or small tree growing to a height of 35 feet (11 m) (rarely to 45 feet or 14 m) with a trunks 8-12 inches (20–30 cm) or more in diameter. The large leaves of pawpaw trees are clustered symmetrically at the ends of the branches, giving a distinctive imbricated appearance to the tree's foliage.


Ecology
Asimina triloba, the pawpaw, commonly grows in floodplains and shady, rich bottomlands, where it often forms a dense, clonally spreading undergrowth in the forest, often appearing as a patch or thicket of individual small slender trees. Pawpaws are not the first to colonize a disturbed site (arriving roughly four years after a clearcut), but may become dominant and slow the establishment of oaks and hickories. Although shade-tolerant, pawpaws do not persist in undisturbed old growth forest. 

Pawpaws spread locally primarily by root suckers; sexual reproduction by seed does also occur, but at a fairly low rate.

Pawpaw flowers are insect-pollinated, but fruit production is sometimes limited as few if any pollinators are attracted to the flower's faint, or sometimes non-existent scent.

The flowers produce an odor similar to that of rotting meat to attract blowflies or carrion beetles for cross pollination. Other insects that are attracted to pawpaw flowers include scavenging fruit flies, carrion flies and beetles. Because of irregular fruit production, some believe pawpaw plants are self-incompatible, requiring cross-pollination between trees of different clones (patches).