pawpaw can be somewhat shrubby or lanky, with a rather thin trunk and branches. However, in full sun, the pawpaw is a dense, pyramidal tree. The leaves are dark green with a golden yellow fall color, large, glabrous, entire, and obovate-oblong (Dirr, 1990). The bark is smooth and grey in color. Buds and leaves are alternately arranged. The pawpaw grows best in soils which are moist but well-drained, high in organic matter, and of slightly acidic pH (Lagrange and Tramer, 1985; Bonney, 2002). The pawpaw naturally reproduces predominantly through root suckering and forms groves or patches, which can be quite large (Willson and Schmeske, 1980).

Pawpaw flower buds are dark brown, pubescent, and formed the previous fall on one-year-old wood (Kral, 1960). The flowers are light green upon emergence, but gradually turn maroon in color, with a slightly fetid odor. Flowers are 2-4 cm in diameter, with 3 outer petals, 3 smaller inner petals, and 3 sepals. Flowers open before the leaves have emerged and expanded, approximately mid-April in central Kentucky. The carpels contain one to several ovules, which give rise to single fruit or multi-fruited clusters (Bailey, 1960). There are usually 3 to 7 carpels per flower, and a round mass of many stamens (Lampton, 1957); however, we have counted up to 12 fruit per cluster on a tree in the KSU orchards (per obs). Pawpaw flowers are protogynous, with the stigmatic surface receptive before pollen is shed from the anthers. This is a mechanism which can force outcrossing.

In the wild, pawpaw has been found to have very low fruit set (Peterson, 1991), with a variety of factors likely responsible. Native stands of pawpaw may be genetically identical as they spread by root suckers. Since pawpaws are believed to require cross-pollination, if genetically different patches or genotypes are not close enough for cross-pollination, fruit set in isolated patches could be low. Willson and Schemske (1980) examined flowering, pollination, and fruit production in a native Illinois pawpaw patch and found a large number of flowers (up to 500 per stem), but low fruit set, ranging from 0.01% to 1.38%. These authors suggested that the low fruit set may have been due to low light levels as an understory tree and thus a low rate of photosynthesis. They also suggested that pawpaws may be self-incompatible, thus leading to low fruit set in a largely clonal patch. Pawpaws are primarily pollinated by flies and beetles (Faegri and van der Piji, 1971). Lagrange and Tramer (1985) also reported low fruit set in wild