The Dynamics of Flowering and Fruit Production in Two Eastern North American Terrestrial Orchids, Tipularia Discolor and Liparis Lilifolia

Liparis lili/olia (L.) Richard and Tipularia discolor (Pursh) Nutall. are common terrestrial orchids in deciduous forests of eastern North America. Although the species have different breeding systems, fruit production in both species is pollinator limited. Liparis is self-incompatible while Tipularia is selfcompatible but anther cap retention promotes outcrossing. Annual variation in the number of plants in flower does not appear to be related to any easily identifiable climatological variable. The number of flowers per inflorescence does not vary greatly in either species. Observed differences in flowering and fruiting are most likely influenced by historical events at the individual level, especially costs associated with sexual reproduction and leaf herbivory. Results from these studies demonstrate the importance of long-term observations to understanding variations in patterns of reproduction of terrestrial orchid species.