Growth and reproduction of American ginseng (Panax quinquefolius) in Wisconsin, U.S.A.

Abstract

The phenology and development of southern Wisconsin populations of wild ginseng (Panax quinquefolius L.) are described. In natural forests, ginseng plants grow slowly, and most plants do not reach reproductive maturity until they are at least 8 years old. Ginseng flowers are perfect, but maturity of male and female reproductive parts is separated temporally in each flower. Ginseng individuals are not obligate outcrossers, and the flowers are visited by generalist pollinators. Exclusion of pollinators did not reduce fruit or seed set. Aging techniques usually underestimate age. Number of leaves (plant stage) is a more appropriate indicator of development than is the number of "annual" stem scars on the rhizome. The number of seeds produced by a plant may be predicted from the number of leaves and the leaf area of the largest leaflet. Accurate estimates of the number of ginseng plants in an area can be made by sampling early in the summer. However, projections of survival and reproductive success in a ginseng population must account for mortality and for plants that senesce early in the summer months before producing seeds. We recommend that ginseng harvesting in Wisconsin be allowed only after September 1 to insure that fruits on mature plants are ripe.