Bruederle, Leo P. , English, Carol .
Pollination biology for the rare Colorado endemic, Penstemon degeneri.
Penstemon degeneri Crosswhite (Plantaginaceae) is a rare Colorado endemic about which little is known. Field research conducted in Summer 2007 confirmed that P. degeneri is capable of self pollination, but that the stigma becomes receptive after the male anthers have released their pollen. Observations on insect visitation and pollinator behavior suggest that effective pollinators include several bumblebee species in family Apidae, and mason bee species in family Megachilidae. Two Apids, Bombus centralis and B. huntii, were the most abundant pollinators. A high percentage of these individuals were more than 80% faithful to P. degeneri flowers, and carried moderate to copious amounts of pollen on their heads and dorsal thorax. Megachilids were less abundant, yet two species, Osmia brevis and O. penstemonis, were 100% faithful to P. degeneri flowers; furthermore, a higher percentage of Megachilid individuals carry copious amounts of P. degeneri pollen on their head and dorsal thorax facilitating contact with the stigma. Megachilids visit fewer flowers and inflorescences per plant per visit as compared to Apids. This suggests Megachilid behavior may promote outcrossing, whereas Apid behavior may promote self-pollination.
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1 - University of Colorado at Denver and Health Sciences Center, Biology, Campus Box 171, P.O. Box 173364, Denver, Colorado, 80217, USA
2 - University of Colorado at Denver and Health Sciences Center, Biology, Campus Box 171, P.O. Box 173364, Denver, Colorado, 80217
Presentation Type: Oral Paper:Papers for Topics
Date: Wednesday, July 30th, 2008
Time: 2:15 PM