Pollination to Population Structure - How Understanding Reproductive Biology Can Inform Conservation of Rare Plants
Berry, Eric .
Reproductive biology and conservation strategies of the endangered New England wildflower Senna hebecarpa (Caesalpiniaceae).
Northern Wild Senna (Senna hebecarpa) is a large herbaceous perennial once widespread throughout New England but now limited to only seven extant populations. The species thrives in moist alluvial soils and its decline has been attributed to forest succession, development, and changes in hydrology. Little is know of S. hebecarpaís reproductive biology, which includes both vegetative production of ramets from rhizomes and sexual production of seeds from bee pollinated flowers. While substantial growth is achieved vegetatively, the plantís dependence upon early successional habitats such as roadsides and flood-prone stream banks means that sexual reproduction followed by seed dispersal to newly disturbed habitats is essential. The objective of this study was to investigate S. hebecarpaís reproductive biology to better understand the role of sexual reproduction in the long-term viability of the species. Flowering and fruiting data were recorded from a wild population in New Hampshire during summer 2008. Given that large clonal stands are prone to self pollination between ramets, data from pollinator exclusion and hand pollination experiments were collected to test for inbreeding depression. Results showed that plantís perfect flowers are self compatible but don't self pollinate without an insect to effect pollination. Self pollination produced fewer fruits per flower than cross pollination. However, germination trials revealed no difference in performance between self and cross pollinated seeds; rather, germination was dependent upon the degree of seed coat scarification. These findings reinforce concerns that mowing and changes in flooding frequency are major habitat threats. Mowing promotes vegetative growth and the development of large clonal stands that are at risk of reduced seed production when rates of self pollination are high. Hydrological changes that reduce flooding limit the vector of dispersal and the mechanism by which seeds are scarified, both affecting the species ability to colonize new areas.
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1 - Saint Anselm College, Biology, 100 Saint Anselm Drive, Manchester, NH, 03102, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Room 3/Woodward
Date: Monday, July 28th, 2008
Time: 9:15 AM