Life History and Reproductive Biology of the Endangered Trillium reliquum

Knowledge of ecological characteristics of rare species is important in assessing their threat status. Trillium reliquum is one of four globally vulnerable North American Trillium species. Yet little is known about the ecology and reproductive biology of T. reliquum. Here we present the first description of the natural history and reproductive biology of T. reliquum. We observed the timing of emergence, flowering, fruit maturation, and seed dehiscence of a population in south-central Georgia (USA). In addition, we conducted a series of pollen manipulation experiments to assess the breeding system and pollen limitation. We found the life history of this species to be similar to other Trillium species; individuals progressed through four morphologically distinct life stages with increases in size and age. However, T. reliquum exhibited an earlier and shorter germination period than other Trillium species and many plants exist in a dormant state during the growing season. This species matured fruit equally well with either cross- or self-pollen and by apomixis. Seeds produced per fruit did not differ among reproductive treatments. The lack of differences in fruit and seed production among pollination treatments suggested there was no pollen limitation in 2004 for this population. The data we report here provide a baseline that can be used to generate assessments of the population stability of T. reliquum.