The pawpaw [Asimina triloba (L.) Dunal] is classified as a member of the Annonaceae, or Custard Apple family. Annonaceae is the largest primitive family of flowering plants, and includes approximately 130 genera and 2300 species (Cronquist, 1981). Other economically important members of Annonaceae include custard apple [Annona reticulata (L)], cherimoya [A. cherimola (Mill.)], and soursoup [A. muricata(L.)]. Most Annona species are native to Central and South America and the Caribbean, with two Annona species [Annona glabra (L.) and A. squamosa (L.)] and two Deeringothamnus species [Deeringothamnus rugelii (B.L. Robins.) and D. pulchellus (Small)] found in southern Florida (Kral, 1960).
Asimina is the only temperate genus in this otherwise tropical plant family. There are 9 species included in the genus Asimina, seven of which are found only in Florida and southern Georgia (Kral, 1960; Callaway 1990). Asimina parviflora (Michx.) Dunal, reaches farther north, into the coastal piedmont areas of the southeastern U.S., including the Carolinas, Virginia, and southern Tennessee. Asimina triloba, or the North American pawpaw, is indigenous to 26 states in the Eastern United States, ranging from New York, southern Ontario, and southern Michigan on the northern boundaries, south to northern Florida, and west to eastern Texas, Nebraska, and Kansas (Callaway, 1990). The North American pawpaw is native to USDA zones 5 (-25°C) through 8 (-10°C) (Peterson, 1991). Pawpaws normally are diploid (2n=18) with triploid mutants (2n=27) found in several sampled populations (Bowden, 1949).
What is now known as Asimina triloba has undergone many name changes throughout the years. Linnaeus originally classified this plant as Annona triloba. Later, Micheaux renamed the species Orchidocarpum arietinum. Only 4 years later, Persoon again transferred the species to Porcelia triloba. Finally, in 1817, Dunal reclassified the plant as Asimina triloba. Torrey and Gray then moved the species to the genus Uvaria, but it was returned to its current and proper name, A. triloba, by Gray in 1886 (Kral, 1960).
The pawpaw is generally found as a small deciduous tree in the understory of mesic forests, reaching 5 to 10 meters in height (Kral, 1960). As an understory tree, the