How people impact medicinal plant evolution: American ginseng (Panax quinquefolius L.) as a case study
Video Health & Life Sciences 2025 Graduate ExhibitionPresentation by Rachel Palkovitz
Exhibition Number 517
Abstract
People utilize bioactive compounds in medicinal plants for traditional and biomedical healthcare practices around the world. My dissertation research examines potential human influences of harvesting and cultivation on medicinal plants from an evolutionary and anthropological perspective, using American ginseng as a case study. I employ a combination of microsatellite genetic markers, physical leaf trait markers, and qualitative interview methods to assess evolutionary change and contextualize human-plant interactions and their potential attendant mechanisms of selection. I compared the genetic and physical trait markers in modern cultivated and wild ginseng populations (N=566 individuals, N=41 populations). I found that growing ginseng under artificial shade has an effect on several ginseng leaf traits with genetic overlap between several cultivated and wild populations. Interviews with ginseng growers revealed a striking imbalance in small-scale growers’ ability to access local seed, driving a pattern of human-assisted gene flow from artificial shade gardens in the midwest to Pennsylvania forests via seed trade. I also assessed variation in quantitative ginseng leaf traits over time using publicly available herbarium specimens (N=1,000 representing 195 collection years, 1820-2015) and found that ginseng specimens declined in size by 35% (General Additive Model smooth term value F=3.857 p=0.00001) and increased in their proportional marginal teeth serration by 25% over the same time period (GAM F=2.726, p = 0.0353). My results highlight contributions of human stewardship to the genetic and phenotypic diversity of the most widely-traded medicinal plant species from North America.
Importance
This research helps scientists, agroforestry professionals, and forest resource policy makers understand the ways that human behaviors such as harvesting and cultivation impact plant species that people use for medicine. Medicinal plant species like ginseng are important for many peoples’ healthcare around the world, especially in traditional and herbal medicine practices, yet current demand exceeds what is sustainable for wild medicinal plant populations. By identifying locally-adapted plant genetics, partnering with large and small-scale medicinal plant farmers, and revealing how medicinal plant traits vary across time and space, this research helps build a pathway for sustainable herbal medicine markets.