Vascular Plants of North Carolina
Account for Common Blue Cohosh - Caulophyllum thalictroides   (L.) Michaux
Members of Berberidaceae:
Members of Caulophyllum with account distribution info or public map:
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Section 6 » Order Ranunculales » Family Berberidaceae
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Author(L.) Michaux
DistributionThroughout the Mountains, and barely into the adjacent foothills; widely scattered over most of the Piedmont except for the northeastern corner.

This is a widespread species of Northern affinity, ranging from eastern Canada south to central VA, northern AL, and AR.
AbundanceCommon in the Mountains; rare in the Piedmont, ranging east to Durham, Wake, and Moore counties.
HabitatThis is a classic Rich Cove Forest species, growing in moist, rich soil conditions. It can occur in other moist or rich montane forests, as well; however, in the Piedmont it is limited mainly to Basic Mesic Forests.
See also Habitat Account for Rich Wet-Mesic Hardwood Forests
PhenologyBlooms in April and May, and fruits in July and August.
IdentificationThis is a quite familiar spring wildflower of our mountain cove forests. It is a somewhat robust herb, growing to about 2 feet on average, rarely to 3 feet tall. From the middle or toward the top of the stem emerge 2 large leaves, each 2-3-times divided, with the ultimate leaflets generally 3-lobed, with entire margins. Each leaflet is 2 inches long and half as wide. There are 1-3 inflorescences from the top of the stem, with small clusters of light greenish-yellow flowers that contain 6 pointed sepals that appear as "petals". Each flower is only about 1/4-inch across. After flowering, the plant produces distinctive medium to rich blue "berries" (drupes), each rounded and about 1/4-inch across, in clusters. The plant is highly distinctive, except for the caviat that some references, including Weakley (2018), separate out a taxon into a full species -- the very similar C. giganteum. That species differs from C. thalictroides by having the sepals ("petals") usually purple instead of yellowish; the terminal leaflets relatively large, about 3 inches long and 2.5 inches wide; and the flowers opening before the leaves expand (as opposed to opening as the leaves expand). That species is rare in NC, known from only a few counties in the mountains.
Taxonomic CommentsMany references include C. giganteum within this species, or as a variety. NatureServe and Weakley (2018) treat it as a good species.

Other Common Name(s)References that lump C. giganteum into this one simply name the species as Blue Cohosh. As a result of having two species, each needs a modifier name, and this one goes mainly by Common Blue Cohosh.
State RankS5
Global RankG4G5 [G5]
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