Caulophyllum thalictroides  (L.) Michx. - Blue Cohosh


 

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Caulophyllum thalictroides - (image 1 of 8)

 

Taxonomy

Family: Berberidaceae

Habitat

Mesic woods.

Associates

Acer saccharum, Actaea pachypoda, Adiantum pedatum, Allium tricoccum, Arisaema triphyllum, Cardamine douglassii, Claytonia virginica, Dentaria laciniata, Dicentra cucullaria, Erythronium albidum, Fraxinus americana, Galium aparine, Geranium maculatum, Hydrophyllum virginianum, Osmorhiza claytonii, Podophyllum peltatum, Prunus virginiana, Quercus rubra, Sanguinaria canadensis, Smilacina racemosa, Tilia americana, Trillium recurvatum, Uvularia grandiflora.

Distribution

New Brunswick west to Ontario and Manitoba, south to SC, AL, and MO.

Morphology

Herbaceous, poisonous perennial to 80 cm, glaucous when young. Leaves arising from a single upright stem, ternate compound with numerous leaflets; leaflets distinctly petiolate. Flowers with 6 green to yellow-brown petals, borne in a terminal panicle-like or raceme-like cyme. Fruit a naked seed with a brilliant blue outer tegument.

Notes

Flowers early April to late May

Wetland indicator: Upland

The specific epithet alludes to the similarity of the leaves to meadow rue. Swink and Wilhelm (1994) describe the unique fruit development of this species as follows, "The ovary wall ruptures early in development by the pressure of the two erect enlarging seeds and withers away. A naked seed is exposed on an expanded stalk, and develops a fleshy outer integument that simulates a drupe. This integument is an iridescent blue which beggars all description." 

References

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Ed.

The New York Botanical Garden. Bronx, NY

 

Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region.
Indiana Academy of Science. The Morton Arboretum. Lisle, Illinois.

 


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Michael Hough 2004