PARENT SESSION
Oral Session # 36: Rare, Threatened, and Endangered Species I: Plants.
Presiding: H Balbach
Tuesday, August 5. 1:30 PM to 5:00 PM, SITCC Meeting Room 204.
Does breeding system contribute to the rarity of Hydrastis canadensis?
Sanders, Suzanne*,1, McGraw, James1, 1 West Virginia University, Morgantown, WV, USA
ABSTRACT- Abundance of Hydrastis canadensis (goldenseal) in the eastern deciduous forest is declining. This decline may be directly or indirectly linked to the breeding system of this species. For example, this species reproduces primarily clonally, forming dense patches. These patches are often separated by great distances, such that obligate outcrossing could limit seed production and/or viability. To test for breeding system type, we implemented treatments on ramets from three natural source populations. To avoid difficulties associated with field pollination, this study was conducted in a greenhouse. The location of flowering ramets were marked at all three source populations in 2001. These were removed in March 2002 prior to emergence and planted in a standard potting mix. Six treatments were implemented. Our results showed that 1) this species is not apomictic, 2) seed set occurred via self pollination, both with and without assistance, 3) seed set occurred via outcrossing with ramets from the same source population and with ramets from other source populations and, 4) seed set of field controls at the source populations was greater than that of the greenhouse treatments. Tetrazolium testing showed that all seeds were viable. These results suggest that breeding system type, and seed production, are not factors limiting the abundance and spread of H. canadensis. However, seedlings are only uncommonly observed in natural populations. Seedlings can be readily distinguished from small vegetative ramets because only cotyledons are produced during the first year of growth. This suggests seed germination may be a factor limiting abundance and spread of this species. Changes in disturbance regimes and/or faunal composition of the eastern deciduous forest may limit seed germination.
Key words: breeding system, Hydrastis, rarity