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Blue Cohosh Caulophyllum thalictroides


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Blue Cohosh - flower
credit: H. Zell/CCSA

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Family: Berberidaceae, Barberry view all from this family

Description Inconspicuous, purplish-brown to yellow-green flowers in a loosely branched cluster.
Habit: native perennial herb; smooth stem, spreads by rhizome, may form large stands.
Height: 8-36 in (0.2-0.9 m)
Leaf: blue-grey-green, lacy, compound and lobed.
Flower: small, daisy-like, not showy, to 0.5 in (12 mm) wide; 3-6 green-yellow to green-purple pointed sepals; held in loose terminal cluster of 5-70 flowerheads.
Fruit: large, deep-blue berry in tight clusters above the foliage.

Warning The berries, roots and leaves of this plant may cause skin irritation if touched, and the raw berries may be poisonous to children if ingested. Sensitivity to a toxin varies with a personís age, weight, physical condition, and individual susceptibility. Children are most vulnerable because of their curiosity and small size. Toxicity can vary in a plant according to season, the plantís different parts, and its stage of growth; and plants can absorb toxic substances, such as herbicides, pesticides, and pollutants from the water, air, and soil.

Flower April to June.

Flower April - May

Habitat Moist shaded sites in eastern hardwood forest: coves, hillsides; to 4000 ft (1200 m); also cultivated as an ornamental.

Range Eastern North America, from Quebec south to Georgia, west to Oklahoma, north to Manitoba; not reported in Alabama.

Discussion Also known as squaw-root, papoose-root. Threatened in Rhode Island. The six stamens and central pistil of this early spring flower mature at different times, assuring cross-pollination. The petals bear fleshy nectar glands that are visited by early solitary bees. The ovary is eventually ruptured by the developing seeds within it; the seeds are thus exposed, an unusual condition among flowering plants. The seeds have reportedly been used as a coffee substitute, but may also be toxic. The foliage resembles meadow rues (Thalictrum), hence the species name.

Comments A heavy wintercoat of mixed leaves should be left on plant in the spring.

Exposure Preference Shade.

Native Distribution New Brunswick to s.e. Manitoba, s. to New England, South Carolina mts., Tennessee & Arkansas

Site Preference Deciduous & mixed woods

Soil Preference Rich, moist, well-drained soils