Interspecific and intraspecific variation in seed size and germination requirements of Sarracenia (Sarraceniaceae)

Seed size and germination requirements of eight (of nine) Sarracenia specie s, and 13 populations of S. purpurea were studied. All species except for S . purpurea are restricted to the southeastern United States, whereas S. pur purea ranges across Canada, southward dong the eastern United States into M aryland and Virginia (S, purpurea sap. purpurea), and from New Jersey south ward into northern Florida and the coast of the Gulf of Mexico (S. purpurea ssp. venosa). I tested the hypotheses that dormancy-breaking requirements vary predictably among species across a latitudinal gradient. I also sought to determine whether seed size and germination requirements were useful ch aracters for resolving systematic and phylogenetic questions within this ge nus. Seed size Varied significantly among species, but variability in seed size within S, purpurea exceeded the variability in seed size observed acro ss all eight species studied. Seeds of all species are morphophysiologicall y dormant upon dispersal. Length of required cool, moist pretreatment varie d among species, and germination in higher latitude populations is enhanced with longer pretreatment. In contrast, variability in germination requirem ents of subspecies, varieties, and populations of the geographically wide-r anging S, purpurea was not related clearly to geographic location (latitude or elevation). Germination requirements do not map onto a proposed phyloge ny of Sarracenia, but observed differences in germination requirements of S . purpurea ssp. venosa var. burkii relative to other populations of S. purp urea support the recent proposal to elevate this variety to species status.