XVI International Botanical Congess

Platanthera lacera is a moth-pollinated, terrestrial orchid. Field studies on a western Illinois population determined the noctuid moth, Anagrapha falcifera (Kby), to be the most frequent and effective pollinator with occasional visits from Allagrapha aerea (Hbn). Measur- ments from 598 spurs indicate that the medium length nectariferous spurs (mean 14.3mm) vary significantly and are not under selective pressure. Experimental pollina- tion showed P.lacera to be self-compatible (94.1%) with a low level of autogamy (8.2%). Visitation rates, assessed by pollinia removal, were relatively high (84.9%) and fruit set on experimental crosses were higher (94.4%) than open-pollinated plants (71.5%), indicating some pollinator or resource limitation. Electrophoretic analysis of 10 enzymes show signs of polyploidy. Further analysis is pending.