Black cohosh (Actaea racemosa L. fmr. Cimicifuga racemosa (L.) Nutt.) is a culturally and economically significant herb native to the eastern forests of North America. Today it is used primarily to reduce the symptoms associated with menopause, especially hot flashes. As the popularity of black cohosh dietary supplements grows, plant populations in the United States face threats from increased wild harvesting and habitat loss. Black cohosh is endangered in Illinois and Massachusetts, listed by United Plant Savers as an “At-Risk” plant and as a top-ranked medicinal plant species of special concern by the Nature Conservancy. The collection of relevant ecological information about this at-risk species is paramount to protecting populations before market forces overwhelm the sustainability of harvests. Given its recent rise in popularity, it is important to consider conservation measures that can prevent possible further habitat loss, habitat degradation, and overharvesting, such as cultivation.
Current cultivation practices de-emphasize the use of locally-adapted seed as a viable planting stock, instead focusing on methods of rhizome propagation and the use of cuttings. Rhizome propagation methods produce clonal plantings with diminished genetic diversity that are less conducive to conservation of the diversity of locally-adapted types.
Results/Conclusions
Scientifically rigorous investigation of the stratification and germination requirements of black cohosh will not only provide valuable insight into the utility of seed-based husbandry for growers, but will effectively investigate the first step in the domestication of a wild medicinal plant.
In the fall of 2008 and 2009, approximately 128,000 seeds were collected from individual open-pollinated black cohosh plants in different physiographic regions of western Maryland, resulting in separate taxa. In 2008, seeds from 92 parent plants were winnowed, counted, weighed, and sorted according to buoyancy. In 2009, seeds from 65 parent plants were added to the study to compare yearly variation. Comparisons across years and populations detected significant variation in seed morphology, buoyancy, germination rate, and seedling characteristics. Seed stratification was consistent with published techniques to break double dormancy. From the 2008 collection, 327 seedlings emerged after 30 days, only 0.5% of all seeds. Bleach treatments showed increased germination when compared to controls. Germination rates across years will be investigated. Developing scientifically rigorous stratification protocols resulting in improved germination rates will encourage cultivation of locally-adapted seed by growers of other medicinal herbs and specialty crops and may provide a method for cultivation of other Actaea L. species.
