Caulophyllum thalictroides (Blue Cohosh)

Plant Info
Also known as: Pappoose-root, Squaw-root
Genus:Caulophyllum
Family:Berberidaceae (Barberry)
Life cycle:perennial
Origin:native
Habitat:part shade, shade; moist, rich woods
Bloom season:April - May
Plant height:1 to 4 feet
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 6-petals Cluster type: panicle

[photo of flowers] 5 or more stalked flowers in 1 or more loose, branching clusters at the top of the stem. Individual flowers are about ½ inch across with 6 yellowish green petal-like sepals and 6 yellow stamens in a ring around the green center. The true petals are tiny (barely longer than the stamens), greenish, and sit between the sepals and stamens.

Leaves and stem: Leaf attachment: alternate Leaf type: compound Leaf type: lobed

[photo of leaves] Leaves are 3 or 4 times compound in groups of 3, each leaflet to 2½ inches long and wide, toothless and hairless, with 2 to 5 pointed lobes and a short stalk. The base of the leaflet is rounded and often asymmetrical, especially on the lateral leaflets. Non-flowering plants have a single compound leaf, flowering plants have 2.

[photo of stem] Leaf and flowering stems are in a whorl at the top of the stem. Stems are erect, multiple from the base, hairless and light green but may be tinged purple or blue and often have a waxy bloom.

Fruit: Fruit type: berry/drupe

[photo of fruit] Fruit is a green, berry-like seed, about 1/3 inch across, that ripens to a deep blue. The fruit is poisonous.

Notes:

Blue Cohosh leaves look similar to some other plants, in particular the Meadow Rues (Thalictrum species) but Blue Cohosh has much larger leaflets and the Meadow Rues lack the whorl of leaf and flower stalks at the top of the stem.

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More photos

Photos by K. Chayka taken at Wild River State Park, Chisago County. Other photos courtesy Peter M. Dziuk.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Laurie - Deer River
on: 2013-08-31 21:33:59

I have a single blue cohosh plant growing amid sugar maple seedlings, red baneberry, and Canada mayflower in a vegetative area under mature sugar maples.

Posted by: Timothy J - Brooklyn Park, Hennepin County
on: 2017-05-08 16:25:47

Lots of these growing on the forest floor of the Izaak Walton League, Breckenridge Chapter property. This mainly oak and basswood forest is on the bluff of the Mississippi River.

Posted by: Jessica - Byron
on: 2018-05-02 14:54:10

Have found these at Oxbow Park in Byron, MN!

Posted by: Donna W - Dakota County
on: 2018-05-07 07:28:45

We have a large natural patch of Blue Cohosh in our back yard which was heavily wooded until we removed the Buckthorn and some Box Elders. I am now worried that this patch is getting too much sun and will have to move it to a spot where there is more shade.

Posted by: Kathy F. - Buse Township, Otter Tail County
on: 2018-08-11 08:07:53

This plant appeared in the moist woods behind our lake cottage after the removal of buckthorn!

Posted by: Holly Hart - Stillwater Township
on: 2018-08-25 14:57:52

I just found a clump in our woods (heavily wooded bluff area overlooking St. Croix River), when clearing out some aggressive raspberry bushes and ground ivy (which was going to smother a walnut tree). Never seen it before and had to look it up!

Posted by: Char Fog - hobart township
on: 2018-08-30 18:36:49

Found a clump next to the driveway with about 5 berries-it was growing in a clump of maple seedlings. We live near a lake.

Posted by: rachel - prior lake, mn
on: 2019-05-10 12:36:52

There is a film on blue cohosh stems that when you touch it with your finger it comes off. I cannot think of the botany term for this "film". please advise. thank you very much Rachel

Posted by: K. Chayka
on: 2019-05-10 16:20:58

glaucous?

Posted by: Diane - Polk county, Rosebud Township
on: 2019-09-02 20:23:29

These are plentiful on my farm. It’s about 30 acres of wooded and wetland. I just was out there today – 1 September 2018.

Posted by: Ron Johannsen - Trenton Lake, Mn.
on: 2020-05-02 13:04:28

Many out now along with other earlier ephemerals.

Posted by: Dan Langseth - Moe Township, Douglas County
on: 2020-08-19 15:31:00

A few plants are present on basswood, ironwood & burr oak forested lake lot west of Alexandria

Posted by: Jennette Spader - Fridley, MN
on: 2020-09-12 23:32:19

There's a large patch on an embankment overlooking Rice Creek at the edge of Locke Park in Fridley.

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