Caulophyllum thalictroides

A woodland plant with bluish leavs and yellow inconspicuous flowers

Caulophyllum thalictroides blue cohosh

Plant grows in the wild/spontaneouslyPlant is native to PA

The flowers of this interesting plant are not showy and blend into the forest background to such a degree that it often takes a sharp eye just to see them. It is a perennial member of the barberry family that grows 1-3 feet high in moist hardwood forests of the eastern United States. In the South it is limited to the mountains. It is found in most counties of the state.

In spite of its lack of bright coloration, it is still an interesting wildflower. The flowers are about ¼ to 1/2 inch in diameter and greenish-yellow in color. I have also seen the flower in a dark brown/maroon color or in an intermediate shade. Apparently, these variations are considered the same species. The flowers have 6 tiny petals, each with 2 glandular nectar glands. These petals grow from the base of 6 larger petal-like sepals. There is a central pistil and six stamens. Under each flower are 3-4 small green bracts that resemble sepals. The flowers occur in clusters of 5-20 but mature at different times, encouraging cross-pollination by early solitary bees. The flowers produce both pollen and nectar as a reward to the insects.

After pollination the ovary forms a capsule that bursts opens to expose 1-2 deep blue fleshy seeds that resemble berries - perhaps the reason for the common name. This rupturing of the ovary is an unusual process for flowering plants. The seeds are toxic to humans, but birds and small mammals will feed on them and help with dispersal. The blue cohosh flower blooms in April or May in Pennsylvania. The plant prefers shady locations.

There are only 2 leaves per flowering plant, but the proliferation of tulip-shaped leaflets makes it look as if there are more. The often bluish-green color of the leaves contributes to the common name of this species. The lower leaf is large and usually divided into 27 leaflets. Each leaflet is 1-3 inches long. The upper leaf is small and divided into 7-12 leaflets, each with 3-6 pointed lobes at the tip. In this manner the leaves somewhat resemble those of the meadow rue.

Young plants are covered with a waxy bloom. The seeds may have been used as a coffee substitute in the past. Extracts of the roots have been used as an herbal medicine, but as in all cases, should be used with great caution, if at all.

Contributed by: Mark Welchley

Grows in moist hardwood forests.

Present in most counties of the state.

Wetland code: Not classified

Flowers April to May.

S-rank: No rank
G-rank:  G5 (Secure)

Caulophyllum thalictroides blue cohosh

Plant grows in the wild/spontaneouslyPlant is native to PA
Caulophyllum thalictroides gallery
Plant Life-Form
perennial forb
Common Names