Negron-Ortiz, Vivian .
The breeding system and reproductive success of two Florida Panhandle federally listed species: Ribes echinellum (Grossulariaceae) and Rhododendron minus var. chapmanii (Ericaceae).
Plant reproductive output can be limited by a variety of factors, both intrinsic and extrinsic. I investigated the reproductive biology of two federally listed shrub species, threatened Ribes echinellum (Grossulariaceae), and endangered Rhododendron minus var. chapmanii (Ericaceae; hereafter R. m. chapmanii). I recorded female reproductive output (flowers produced, fruit set) and plant size (number of stems, height) for both species, and used hand-pollination experiments to determine the breeding system of R. m. chapmanii. Rhododendron m. chapmanii flowers emit a faint odor, bear nectar, and produce abundant pollen borne on viscin threads. For both species, flowers are protandrous and bumblebees were the only floral visitors observed. Pollination efficiency and reproductive success, however, differed strongly between these two species. Reproductive output for R. m. chapmanii was not significantly different between the two census years (2008, 2009). However, R. echinellum exhibited a marked decline in reproductive output during the two-year study. In 2008, 22 % of the plants produced flowers and 18 % produced fruits. In 2009, 5% of the plants produced flowers; however, the proportion of plants producing fruits was reduced to less than 1%. Eighteen percent of the R. echinellum plants were not found in the 2009 census year; these plants are presumed dead, most likely resulting from drought or fire suppression. Of the plants that were found, 68% lacked green shoots. These plants are either allocating to storage/root growth or are dead. Currently, I am investigating the breeding system of R. m. chapmanii. Conservation implications of the reproductive ecology of these species will be discussed.
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Florida Panhandle federally listed plants
1 - U.S. Fish & Wildlife Service, 1601 Balboa Ave, Panama City, FL, 32405, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Wasatch A/Cliff Lodge - Level C
Date: Wednesday, July 29th, 2009
Time: 8:00 AM