Drosera rotundifolia is a carnivorous plant found in wetland habitats throughout Canada and the northern US. Two extreme southern disjunct populations are found in Colorado, one in Gunnison county, and the second in Jackson county. Due to their unusual disjunct distribution, both populations are listed as sensitive by the USFS. Little is known about flowering and reproduction in these Colorado populations, but historical reports suggest that the Gunnison county population may be primarily cleistogamous. The objective of this study was to collect data on phenology and reproduction to shed light on the mating system of this unusual population. In the summer of 2000 flowering phenology was closely monitored. The population was visited 2-3 times per week throughout the flowering season and visits were made at different times of day. We also collected data on the types of insects captured and the rate of capture. At the end of the season seed capsules were collected and examined. On average, plants in this population capture one insect per week. The insects captured are pirmarily small dipterans. Larger prey may be robbed from D. rotundifolia by ants. Though floral buds were prolifically produced, only one open flower was observed. However, the majority of capsules collected produced seed. We hypothesize that this population is primarily cleistogamous, possibly as a result of a historical population bottleneck.

Key words: Drosera rotundifolia, carnivorous plants, cleistogamy, Droseraceae, kleptoparasitism, mating systems