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 (table 1). Some plants from eastern Asia and the Aleutian Islands had more distinctly clawed sepals than those from eastern North America but this was not evident on all individuals. Seeds from eastern North American plants were found to be variable in shape, with all seeds having at least one angle in cross section.
Table 1. Morphological comparison of Coptis trifolia from the Aleutian Islands, the rest of North America, and Asia.
Other
Aleutians N. Amer. Asia
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Petiolules (mm) 0.3-0.8 0.5-3.5 0.5-3
Sepals (mm wide) 1.7-2.9 1-3.6 1.8-4.5
Nectaries (L:W ratio) 0.9-1.3 0.8-1.3 0.9-1.6
Follicle
bodies (mm) 3.9-5.3 4-7 4.8-5.5 Follicle beaks (mm) 3-3.5 2.3-3.8 2.2-3 Native Americans used various preparations made from the roots of Coptis trifolia medicinally to treat stomach cramps, jaundice, sore mouth and throat, gum problems, and worms, to stop vomiting, especially for children, as eyedrops, for teething, and as an astringent (D. E. Moerman 1986).
