Population structure, pollination biology, and reproductive output of dioecious Smilax herbacea were studied in nearly 900 individuals from 11 populations in Connecticut over a three year period. Reproductive plants comprised about 60% of an average population, with nearly 65% of these male. Percentages of either sex did not vary across sites or between years. Female mortality is suggested as the most likely reason for the strong male bias (2.3 male:1 female). Male plants, although smaller, had twice the number of inflorescences and 68% more flowers than female plants. Both inflorescence and flower number were significantly correlated with plant size in male, but not in female plants, implying inflorescence and flower production were less constrained in male plants. Although population size and population density of both female and male plants varied significantly across sites, plant gender and density were uncorrelated with site size. However, a significant interaction was detected between the density of each sex and the site of occurrence. Smilax herbacea can be characterized as a generalist in its attraction of pollinators. The carrion-like odor of male and female tepals and the pollen reward of the staminate flowers attract bee, beetle, and fly visitors. Due primarily to their high mobility and pollen carrying capacity, andrenid and halictid bees and anthomyiid and stratiomyiid flies are considered major pollinators. No significant difference in fruit set among populations was detected. Less than 1% of intrapopulational fruit set variation was explained by either site size or by plant density, nor was male plant density significantly correlated with fruit set. Furthermore, experimental interpopulational crosses did not significantly increase fruit set. These facts imply resource rather than pollen limitation in female plants.

Key words: dioecy, pollination biology, reproductive output, resource limitation, Smilax herbacea