Reproductive Biology of the Federally Endangered Clematis morefieldii Kral (Ranunculaceae)

Successful management of rare plant species requires understanding of reproductive life history. To assess reproductive attrition, the status of all reproductive units (expressed in seven stages) on 40 plants at The Nature Conservancy's Keel Mountain Preserve (Madison County, Alabama) was recorded throughout 4 yr (2009-12). Floral herbivory by Lepidopteran larvae (Geometridae) and abortion of reproductive units was common, with few flower buds (< 12%) producing mature fruits and the greatest attrition occurring during the smallest flower bud stage. Reproductive output was positively correlated with peak growth season rainfall (April June); plants produced more fruits in wet years (2009 and 2011) than in drought years (2010 and 2012). Postdispersal achene predation assessed in a high-density Clematis area and a low-density Clematis area reached 15% after 1 wk and increased to 30% after 4 mo but did not significantly differ between high-density and low-density areas. Germination was documented by planting achenes in cages in high-density and low-density areas. Seeds remained dormant the first year and germinated in significantly greater amounts the second year (23%) compared to the third year (9%) after planting. Germination did not differ between high-density and low-density areas. This study documented high levels of floral herbivory, demonstrated the importance of growing season rainfall, revealed moderate levels of postdispersal achene predation, and confirmed the existence of a short-lived seed bank. Land managers can use these results to design management strategies to boost reproductive success of plants in declining or small populations.