Overall At-Risk Score: 45
Blue Cohosh; Papoose Root, Squaw-root
Berberidaceae (Barberry family)
Purple-green flowers bloom in mid-April, ripening into a brilliant blue fruit that holds onto the plant through summer. Each fruit has two seeds that outgrow the fruit shortly after seed development begins, breaking the wall and growing into large blue seeds positioned above the leaves. These seeds are primarily dispersed by birds.
Found from Manitoba to northern Arkansas and Quebec to South Carolina – specifically in the U.S. in Arkansas, Delaware, Illinois, Indiana, Iowa, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, North Carolina, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia, and Wisconsin and the Canadian provinces of Manitoba, New Brunswick, Nova Scotia, Ontario, and Quebec.
Blue Cohosh needs shaded areas and rich, moist soil. It is found almost entirely in the southern portions of the Eastern Hardwood Forest.
Ability to Withstand Disturbance and Overharvest:
Blue Cohosh requires moist soils and deep shade, which means logging in forestlands is a threat to Blue Cohosh populations. Overharvesting is also a threat, as Blue Cohosh seeds may take up to three seasons to germinate.
Status of Endangered/Threatened (by state):
Caulophyllum thalictroides is listed as “Threatened” in the state of Rhode Island.
Caulophyllum thalictroides has not yet been evaluated by the IUCN Red List.
Part of Plant Used/Active Medicinal Compounds:
The primary medicinal compounds of C. thalictroides are Magnoflorine and Sparteine, and it was used historically for heavy periods and rheumatism, as well as gastrointestinal issues. It is important to note that touching Blue Cohosh can cause skin irritation, and many parts of the plant are toxic if eaten in large amounts, leading to nausea and diarrhea.
Demand and Relative Acreage Needed to Meet Demand:
Demand for Blue Cohosh root is very low compared to many of our native perennial herbs, but it is steadily growing.
Wild Harvesting Impact On Other Species and Lookalikes:
Caulophyllum thalictroides is often confused with a similar species, Caulophyllum giganteum, or Giant Blue Cohosh, which has a similar leaf shape and growth pattern. But C. giganteum is significantly larger than C. thalictroides and has consistently dark purple flowers, and flowers 2-3 weeks earlier. Not much research has been done on C. giganteum, but it appears that it may not contain as many of the active compounds found in C. thalictroides.
C. thalictroides also shares a lot of visual similarities to the meadow rues (Thalictrum) and is difficult to distinguish without visible flowers or fruit. But meadow rues often have much longer petioles connecting the leaflets to the main stem.
Recommendations for Industrial and Home Use:
Consumers should talk to their doctors before taking Blue Cohosh and rely on sustainably farmed sources rather than wild-harvested roots. It is possible to grow Blue Cohosh in your own shade garden, and there are several sources of Blue Cohosh seeds available for purchase online.
- Densmore, Frances, 1928, Uses of Plants by the Chippewa Indians, SI-BAE Annual Report #44:273-379, page 344.
- eFloras, (n.d.), Caulophyllum thalictroides in Flora of North America, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA. Retrieved August 12, 2019, from http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500331
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- Lady Bird Johnson Wildflower Center, (2019, January 24), Plant Database: Caulophyllum thalictroides, Retrieved August 12, 2019, from https://www.wildflower.org/plants/result.php?id_plant=cath2
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- USDA. (n.d.). Plants Profile for Caulophyllum (cohosh). Results compiled from multiple publications. Retrieved August 12, 2019, from https://plants.usda.gov/core/profile?symbol=CAULO
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