Schultz, Angela , English, Carol , Bruederle, Leo .
Pollen-ovule Ratios as an Indicator of Breeding System in Penstemon degeneri.
Pollen-ovule ratios are an important aspect of the pollination biology of a species, and can provide insight into breeding system. A relationship exists between the number of ovules that a flower produces relative to the amount of pollen production. For example, xenogamous (out-crossing) species have been shown to produce a large volume of pollen relative to the number of ovules – resulting in a high pollen-ovule ratio – that better ensures pollination and seed set. Prior evidence from research on the reproductive biology of Penstemon degeneri Crosswhite (Plantaginaceae), a rare Colorado endemic, suggests that this species has a mixed mating system involving out-crossing by a suite of megachilid bees, apid bees, and vespid wasps, as well as self-pollination. Herein, pollen-ovule ratios are used to further test the hypothesis of facultative xenogamy in this species. Pollen and ovule counts (or estimates) were obtained from 40 individuals representing three populations across the elevational range for this species. Ovule counts ranged from 64.1 (Â± 17.1) – 102.9 (Â± 19.8), while pollen-ovule ratios ranged from 963.3 (Â± 217.5) – 1291.5 (Â± 411.7) pollen grains/ovule. These data support our previous results that P. degeneri is facultatively xenogamous – predominately outcrossing, while still capable of self-pollination.
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1 - University of Colorado Denver, Biology, Campus Box 171, PO Box 173364, Denver, CO, 80217-3364, USA
2 - University of Colorado at Denver and Health Sciences Center, Biology, Campus Box 171, P.O. Box 173364, Denver, Colorado, 80217, USA
Presentation Type: Poster:Posters for Topics
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM