Actaea racemosa L.

Black Cohosh


CC = 7
CW = 5
MOC = 25

© DETenaglia

Family - Ranunculaceae

Habit - Rhizomatous perennial forb, sometimes with a woody base.

Stems - Erect, to 2.5 m, glabrous, glaucous, green but often purple at the nodes.

Actaea_racemosa_node.jpg Purple node.

© DETenaglia

Leaves - Basal and alternate, petiolate, 2 times pinnately compound, glabrous, to 1 m broad, the leaflets ovate to broadly lanceolate, toothed and irregularly sharply lobed, green adaxially, silvery-green abaxially, with a few hairs abaxially on the veins, the largest leaflets 5-10 cm long, 3-7 cm wide. Veins of leaflets impressed adaxially. Leaves of the flowering stem reduced to bracts.

Actaea_racemosa_leaf2.jpg Leaf.

© SRTurner

Inflorescence - Panicles with 2 or 3 racemelike branches, 15-43 cm long. Axis of the inflorescence tomentoulose. Flower stalks 4-6 mm long, 0.2-0.5 mm wide, densely pubescent with soft contorted hairs, subtended by minute bracts.

Actaea_racemosa_inflorescence.jpg Inflorescence

© DETenaglia

Actaea_racemosa_inflorescence2.jpg Inflorescence

© SRTurner

Flowers - Actinomorphic, perfect. Sepals 3-5, greenish white, 2-6 mm long, plane or somewhat concave, not persistent at fruiting. Petals 4-10, white or cream-colored, 2-4 mm long, plane. Stamens numerous, showy, the anthers white or yellow. Staminodes absent. Pistils 1-8, each with 4 to numerous ovules. Stigma 0.5-1.0 mm wide.

Actaea_racemosa_flower.jpg Individual flower.

© DETenaglia

Fruits - Follicles, 1 per flower stalk, 5-10 mm long, ovoid or ellipsoid. Seeds semicircular, smooth or ridged.

Actaea_racemosa_fruits.jpg Fruits.

© SRTurner

Flowering - June - July.

Habitat - Mesic upland forests, often in rocky places, bases of bluffs, mostly on calcareous and cherty substrates.

Origin - Native to the U.S.

Lookalikes - None when flowering. Vegetatively resembles A. pachypoda.

Other info. - This distinctive species can be found across much of the southern third of Missouri, and eastward from Missouri into the northeast and Canada. When in bloom, the plant is easy to ID in the field because of its big leaves and long inflorescences. The plant also has a foul odor, especially when in flower.

This species has a long tradition of medicinal use by Native Americans, and more recently for women's health purposes including treatment of symptoms of menopause, premenstrual syndrome (PMS), painful menstruation, acne, osteoporosis, and for inducing labor. The plant may also have anti-inflammatory properties. However, controlled clinical trials have thus far failed to show a consistent benefit. The plant contains a large number of compounds having potential physiological activity, and these can occur in widely varying amounts and proportions. It is certainly possible that further research will reveal useful medicinal properties of the plant or one or more of its chemical constituents. The plant is considered toxic, so any use as a medicinal herb must be based on a solid understanding of the appropriate dosage and awareness of the potential risks.

Photographs taken at the Current River Conservation Area, Reynolds County, MO., 6-26-01, and at Big Spring Park, MO., 7-1-03 (DETenaglia); also at Johnson's Shut-Ins, Reynolds County, MO, 6-26-2015 and 10-1-2018 (SRTurner).