Geographic Variation in Size and Reproductive Success in the Paw Paw (Asimina Triloba)

Abstract

The size, sexual performance, and habitat of the paw paw tree (Asimina triloba) were analyzed at three sites between the center and the northern portion of its geographic range. Maximum girth and height occurred in stands on moist shady sites regardless of geographic location. In the northern part of its range the paw paw was restricted to such sites, but toward the center paw paws occupied unshaded, relatively dry sites as well. Flowers were abundant in all stands studied, but fruit set was nil in the north and highest at the center. We suggest that geographic variation in fruit set may be due to low pollination success in the north, caused by the scarcity and isolation of paw paw stands coupled with protogyny and highly synchronous flowering.