Plants of the Eloise Butler Wildflower Garden

Blue Cohosh is a native erect perennial forb growing from one to over two feet high on smooth mostly cylindrical stems, unbranched below the inflorescence.

The leaves differ between plants that flower and those that do not. Non-flowering plants produce a single compound leaf at the top of the stem. Flowering plants produce a second leaf from the middle of the stem that is usually somewhat larger than the first leaf which, in a flowering plant, is located directly under the inflorescence. The leaves have from 3 to 4 (3 usually) 3-part sections, each section then divided into 3 sub-sections which are in turn divided into 3 egg shaped leaflets that when mature have several prominent lobes at the top - usually 3 but up to 5. [Thus 9 leaflets per section and 27 leaflets per leaf.] The leaf rising from the stem top is the reason for the genus name. At first they are a smoky-green then turning to a light to medium bluish-green; they are without hair and have pinnate to palmate venation. Leaves are easily detached from the stem so use care in the home garden or you will have nothing but an upright stick.

The inflorescence is a branched terminal cluster, called a cyme, at the top of the stem and above the main leaf, containing 5 to 70 flowers, but usually less than 30.

Flowers: The entire individual flower is very small - only 3/8 to 1/2 inch wide. The 6 sepals of the flowers are of green to purplish color, not the blue you might expect from the name - the blue refers to the fruit; these are elliptical in shape with the tip somewhat flexed backward and look like petals, except that the petals are actually tiny, appearing at the base of the longer sepals. They have a fan-shape, are greenish-yellow and bear nectar. The 6 stamens are symmetrical (not alternate) with the petals and sepals and have short greenish-yellow filaments and a two-section yellow anther. Thus, each sepal lines up with a petal and a stamen. The ovary is ovoid with a single style. Under the flower are 3-4 small bractlets that look like sepals but soon drop away.

Fruit: Each fertile flower produces 2 seeds, fleshy initially, but the ovary then ruptures and the seeds, which form in early summer, harden and stay on the plant till the following spring unless eaten. Each is about 1/3 inch wide and as the fruit matures the seed stalk elongates. "Blue" refers to the color of the mature seed coat. Fruit color is first green but darkens over the summer into blue and by late fall and early spring, if still present, is quite striking. The seeds are best planted in the fall and let nature handle the germination requirements, which may take some time.

Habitat: Blue Cohosh grows from a somewhat lumpy rhizome. It is an early spring flowering plant that blooms in the dappled sunlight under the tree canopy before tree leaf-out. Fertile neutral to slightly acidic soil with adequate moisture is needed and then light shade during the summer months. Spreading of the root slowly establishes more plants and division of the root is best for transplants as seeds are hard to start and new plants do not flower for 3 to 4 years.

Names: The genus name, Caulophyllum, is taken from two Greek words - caulos for 'stem' and phyllos for leaf', together referring the leaf being attached right at the top of the stem. The species name, thalictroides, means 'like thalictroides' and refers to the resemblance of the leaves to the Meadow Rue, Thalictrum dioicum, which has similar 3-parted leaf sections. Also, the common name of Cohosh comes from the Algonquin word that means 'rough,' which is a description of the texture of the root. The other common names of Papoose-root and Squaw-root are probably derived from folk medicine where a decoction of the root was said to greatly relieve the pains of childbirth.

The author names of the plant classification are: First to classify was '(L.)' which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. His work was amended by ‘Michx.’ which refers to Andre Michaux (1746-1802), French botanist who made many exploring expeditions in the U.S. collecting and cataloging many species. Two important works of his are the Histoire des chênes de l'Amérique septentrionale (1801 - Oaks of North America), and the Flora Boreali-Americana (2 vols., 1803). His son Francois, traveled with him and the father’s notes were later used for the 3-volume North American Sylva.

Uses: See notes below for lore. The plant is not grown for flowers as they are small and not colorful but rather for the foliage and the colorful berries. White-tailed deer and other browsers tend to avoid the plant due to the bitter taste of the foliage.