Pollination Biology of the Federally Endangered Echinacea laevigata (Boynton and Beadle) Blake, Smooth Coneflower, in Small, Isolated Populations

Abstract

Echinacea laevigata (Boynton and Beadle) Blake, a federally endangered species, occurs in several small, isolated populations and a single large population in the northern Piedmont of North Carolina. Currently, little is known of the reproductive biology of this species. Therefore, we sought to describe its flowering phenology, compatibility pattern, and which of its various flower visitors were the more effective pollinators, to inform conservation efforts. In addition, pollinator limitation can reduce seed number and seed quality in small, isolated plant populations. We conducted a study of insect flower visitation and seed production in these populations to test our hypothesis that plants in the small, isolated populations are visited by fewer insect taxa, receive fewer visits, and produce fewer and/or less fit seeds than do plants in the large population. Our data show that average insect visitor species richness was significantly greater in the large population than in small populations and all but one of the small populations had fewer pollinator visits per head during fifteen minute observations than the large population; however, plants in several small populations produced as many or more seeds per head than did plants in the large population. Therefore, our results were not consistent with expectations of pollinator limitation. However, results show that seeds from small populations produce seedlings that are less fit as those from the large population. We conclude that other factors not examined in this study are more threatening to small, isolated coneflower populations than is pollinator limitation.