Jones, Marry , Liu, Sean C. , Leong, Joan M. .
Nectar composition and petal size variation in an endangered plant species, Sidalcea pedata.
GYNODIOECY is known to occur in at least 543 plant species, including many species of the genus Sidalcea. Species with this type of breeding system exhibit two distinct morphs: hermaphrodites and females. Female flowers generally have smaller petals and produce only ovules, whereas hermaphrodite flowers exhibit larger petals and produce both pollen and ovules. Recent studies of the federally endangered Sidalcea pedata indicate that like other species of Sidalcea, S. pedata is gynodioecious. S. pedata (Bird-foot Checkerbloom) is confined to the montane meadows of the Big Bear region of California. Previous observations indicate that insect pollinators, such as bumblebees and honeybees, visit hermaphrodite flowers of gynodioecious S. pedata more frequently than females. Furthermore, observations of floral visits revealed that insect pollinators were actively probing for nectar in both morphs rather than pollen. The objectives of the study are to examine if there is a difference in sugar composition between the two morphs of S. pedata, to determine the relative amount of nectar in each morph, and to examine if pollinator attraction to a particular floral morph is due to the difference in petal size between the two morphs and is independent of the presence of pollen. Preliminary data suggests that hermaphrodite flowers of S. pedata have higher fructose and glucose contents in the nectar than females; therefore, an insect preference for a particular sexual morph may be related to variation in nectar rewards. Furthermore, hermaphrodites average larger corolla diameter (Bluff Lake 16.15, Lot K 15.79 mm) than females (Bluff Lake 9.66 mm, Lot K 8.44 mm) at both sites. However, manipulations of the hermaphrodite flowers revealed that insect pollinators appear to be attracted to trimmed hermaphrodite flowers rather than female flowers. Understanding the features that entice foraging pollinators to visit flowers will allow us to better manage this endangered species.
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1 - California State Polytechnic University, Pomona, Biological Sciences, 3801 West Temple Avenue, Pomona, California, 91768, USA
2 - California State Polytechnic University, Pomona, Chemistry, 3801 West Temple Avenue, Pomona, California, 91768, USA
endangered plant species
plant-insect pollinator interaction
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM