POLLINATION BIOLOGY,SELF-INCOMPATIBILITY,AND STERILITY IN IPOMOEA PANDURATA (L.) G. F. W. MEYER (CONVOLVULACEAE)

Ipomoea pandurata rarely produces seed. Sporophytic self-incompatibility is a secondary factor contributing to the reduced seed production because the principal pollinators, Bombus pennsylvanicus (Apidae) and Melitoma taurea (Anthophoridae), effect cross-pollination in most populations. Sterility, expressed as pollen tube failure in the style and as a sterility mechanism in the ovary, is the primary factor accounting for reduced seed production. It is difficult to reconcile the extensive geographical distribution of I. pandurata with this sterility.