Spreading and bushy when mature, blue cohosh is a large, many-stemmed perennial, 1-3 ft. tall. Thrice-compound leaves with lobed leaflets are purplish in spring. Inconspicuous, purplish-brown to yellow-green flowers in a loosely branched cluster. Clusters of flowers are followed by conspicuous, bright-blue berries.
The six stamens and central pistil of this early spring flower mature at different times, assuring cross-pollination. The petals bear fleshynectar 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.
Size Class: 1-3 ft.
Bloom Color: Yellow , Green , Brown
Bloom Time: Apr , May
USA: AL , AR , CT , DE , GA , IA , IL , IN , KS , KY , MA , MD , ME , MI , MN , MO , NC , ND , NE , NH , NJ , NY , OH , OK , PA , RI , SC , SD ,TN , VA , VT , WI , WV
Canada: NB , NS , ON
Native Distribution: N.B. to s.e. Man., s. to New England, SC mts., TN & AR
Native Habitat: Deciduous & mixed woods
Water Use: Medium
Light Requirement: Shade
Soil Moisture: Moist
CaCO3 Tolerance: Low
Soil Description: Rich, moist, well-drained soils
Conditions Comments: A heavy wintercoat of mixed leaves should be left on plant in the spring.
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. POISONOUS PARTS: Raw seeds, roots. Low toxicity if ingested. Symptoms include vomiting and diarrhea. Toxic Principle: Alkaloid and saponins. (Poisonous Plants of N.C.)
Conspicuous Flowers: yes
Seed Collection: Not Available
Seed Treatment: Scarifing seeds by nicking the seed coat will hasten germination.