Coptis trifolia

FNA (1997, vol. 3), Aiken et al. (2007), Reznicek et al. (2011), Broillet et al. (2026), and Native Plant Trust (2026) do not recognize subspecies of Coptis trifolia.

Per FNA (1997, vol. 3): "M.L. Fernald (1929) treated plants from Greenland and eastern North America as Coptis groenlandica and those from Alaska and eastern Asia as C. trifolia. He did concede, however, that intermediates do occur. E.Hultén (1937) treated the two taxa as subspecies but concluded that C. trifolia subsp. trifolia was restricted to the Aleutian Islands in North America. Plants from southeastern Alaska were comparable to material from Greenland and were called C. trifolia subsp. groenlandica. Hultén (1944) later reversed this decision, concluding that the differences between the two subspecies were too slight to warrant their continued recognition. Finally, R. L. Taylor and G. A. Mulligan (1968), in their study of North American Coptis, found that the two subspecies could be distinguished on the basis of sepals and seed shape: subsp. trifolia having clawed petals and quadrate seeds; subsp. groenlandica possessing sepals that gradually narrow toward the base and round seeds.

Petiolule length, sepal width, the length-to-width ratio of the nectary, follicle body and beak length, and sepal and seed shape have been used most commonly to distinguish these two taxa. My comparison of herbarium specimens from the Aleutian Islands, the rest of North America, and eastern Asia indicated that no clear distinction could be made."

This widespread species is relatively frequent in the northern portion of its large, generally boreal range. It is sensitive to ecological disturbance and is sometimes collected from the wild for medicinal use. Given the large range for this species, it is estimted that there are 300+ occurrences, more than 100,000 plants worldwide, and at least 13 protected sites, if not more than 40.

Coptis trifolia occurs from Greenland across North America to Alaska, including most of Canada and the eastern U.S. C. trifolia also occurs in northeast Asia to northern Japan (Kartesz and Meachum 1999, M. Stein (BLM) 1998). There are two disjunct populations in western United States, in the states of Washington and Oregon.

Coptis trifolia is considered common in Canada, its main North American range. It is considered rare in Oregon where it has been designated as a sensitive species (pers. comm. J. Kagan, December 2001). This species is more frequent in western than eastern British Columbia (Douglas et al. 1990). In the eastern U.S., Coptis trifolia is rare in North Carolina, but reportedly more common in the northeast (Rhoads and Block 2000).

Many activities pose a threat to this understory species, such as logging, hydrologic change, soil disturbance and possibly high intensity fires; this species is collected to a certain extent for medicinal use, but collection probably does not pose a significant threat at this time across its range. Populations in Oregon, and perhaps other regions in western North America are relatively rare, so collecting in these areas could be detrimental to local populations. A related Asian species, Coptis sinensis, is cultivated for commercial use (Tilford 1998).