BINGHAM, ROBIN A.* and NANCY D. COHEN. Department of Natural and Environmental Sciences, Western State College, Gunnison, Colorado, 81231, USA. - Flowering, reproduction, and kleptoparasitism in an extreme southern disjunct population of Drosera rotundifolia.
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
Key words: Drosera rotundifolia, carnivorous plants, cleistogamy, Droseraceae, kleptoparasitism, mating systems