Patterns of Dioecism in the Flora of the Carolinas

Abstract

Dioecious seed plants of North and South Carolina are identified and classified as to growth form, longevity, trophic condition and moisture affiliation. The dioecious species constitute 3.5% of the Carolina flora, a value within the range reported for other temperate floras. More dioecious species are trees, shrubs and vines, and fewer are herbs, than would be predicted from the null hypothesis that dioecious species should be represented in these categories in the same proportions as species in the total flora. Similarly, more dioecious species are perennials and biennials, and fewer are annuals, than predicted. There also appear to be a disproportionately large number of dioecious heterotrophs. The greatest number of dioecious species is found in mesic terrestrial habitats. Several hypotheses are advanced as possible explanations for these patterns in dioecism.