Cypripedium acaule

Cypripedium acaule is a perennial orchid occurring on acidic soils in bogs, forests, barrens, heath, and roadsides of North America, from Alberta east to Newfoundland, Canada, south to Georgia and Alabama in the United States. Threats to this species include development, competition from exotics, alteration of forest habitat through fire suppression, and collection from the wild for horticultural or medicinal purposes. This plant may be somewhat reproductively-limited and exhibits low flowering rates. However, given its large range extent, large number of occurrences, abundant habitat, and broad habitat preferences, Cypripedium acaule is considered secure.

Cypripedium acaule occurs in North America, from Alberta east to Newfoundland, Canada south through Georgia and Alabama in the United States (FNA 2002, Weakley and the Southeastern Flora Team 2025). Range extent was estimated to be over 6.6 million square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).

By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are several thousand occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).

Threats to Cypripedium acaule include habitat destruction as a result of development, competition from exotics such as Japanese honeysuckle, and alteration of forest habitat through fire suppression (Patrick et al. 1995). Though Cypripedium acaule is advertised by several distributors as being nursery-propagated, exploitation of wild populations has occurred in the past (Patrick et al. 1995), and the plants continue to be actively collected for sale (Deborah White, pers. comm., 2002). Uses are apparently both horticultural and medicinal. The roots of C. acaule have been used as a sedative, and it is reportedly being sold by "a few companies" despite the 1988 request by the American Herbal Products Association that its members cease using wild-harvested Cypripedium (Medicinal Plant Working Group 2002). In addition, the species is showy and a popular subject for sale in large commercial growers' outlets (often the roots and rhizomes of these plants are sold in such poor condition that the plants will not survive). In some areas, natural populations may be devastated by these practices (Tom Patrick, pers. comm., 2002). At least in eastern Canada, however, the plant remains so common that only a "massive" amount of collecting would impact populations beyond a very local scale (Sean Blaney, pers. comm., 2002).