Woods, Teresa M. , Hartnett, David C. , Ferguson, Carolyn J. .
Multiple reproductive modes contribute to fitness homeostasis of the invasive Lespedeza cuneata (Fabaceae).
Studies comparing congeneric native and exotic species prove fruitful in investigating plant traits that foster invasion. Using this approach, we examine the complex reproductive system of the invasive Lespedeza cuneata (Dum.-Cours.) G. Don in relation to three native congeners in the variable environment of the North American tallgrass prairie. Lespedeza species produce both chasmogamous (CH) and cleistogamous (CL) flowers, and propagate clonally via vegetative buds. Utilizing multiple natural populations over two years, we investigated reproductive modes of individuals from bagged and unbagged treatments of each species. We found that , L. cuneata produced one hundred times as many CH flowers, five times as many seeds and a significantly greater number of vegetative buds than any native studied. Insect visitation significantly affected seed set in CH flowers, though some autonomous CH selfing occurred in all species. The invasive relied relatively less on selfing than the natives and exhibited less variation in both sexual and asexual modes of reproduction, maintaining a diverse strategy more consistently and productively than the native species, while the natives responded to environmental variability with more phenotypic plasticity through resource allocation. We document a little-understood strategy of delayed self-pollination in the chasmogamous flowers of three of the four species, including the invasive, which allows the plants to set seed in chasmogamous flowers even when pollinators do not visit, further contributing to reproductive assurance. We conclude that a diverse reproductive biology and a wide regeneration niche in relation to its native congeners confers fitness homeostasis and likely allows L. cuneata to successfully spread under a wide range of conditions.
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1 - Kansas State University, Herbarium and Division of Biology, Ackert Hall, Manhattan, Kansas, 66506-4901, USA
2 - Kansas State University, Division of Biology, Ackert Hall, Manhattan, Kansas, 66506-4901, USA
mixed mating system.
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Ontario/Hilton
Date: Monday, July 9th, 2007
Time: 1:45 PM