blue cohosh

(Caulophyllum thalictroides)

               
Conservation Status

IUCN Red List

not yet assessed

blue cohosh

NatureServe

N4N5 - Apparently Secure to Secure

SNR - Unranked

Minnesota

not listed

Nativity

Native

Occurrence

Moist. Woods.

Habitat

 

Flowering

April to May

     
Flower Color

Yellowish green

     
Height

1 to 3

     

Identification

This is a 1 to 3 tall, erect, perennial forb that rises on multiple stems from a rhizome.

The stems are erect, hairless, and unbranched. They bear just 2 leaves, the first just above the middle, the second just below the inflorescence.

The first leaf is compound, triternate, and stalkless. It divides at the base into 3 long stalks. Each stalk is again divided into 3 shorter stalks. At the end of each of these shorter stalks are 3 leaflets. The overall appearance is of 3 biternate leaves. The 27 leaflets are broad, inversely egg-shaped, 2 to 3 long, and ¾ to 4 wide. They are usually 2- to 5-lobed near the tip, but they may be unlobed. When young they are covered with a whitish, waxy coating. The margins are untoothed. The upper and lower surfaces are hairless. The second leaf is similar to the first but smaller.

The inflorescence is a small, branched cluster of 5 to 70 flowers at the end of the stem.

The flowers are to ½ wide. There are 3 or 4 sepal-like bracts that drop early. There are 6 petal-like, yellowish green, widely spreading sepals. The 6 petals are reduced to gland-like nectaries, are opposite the sepals, and are much shorter than the sepals. In the center of the flower are 6 stamens with yellow anthers surrounding a green ovary.

The fruits never develop. Two large growing seeds rupture the ovary. The seeds are borne naked in pairs on short stems at the end of the elongated pedicel above the leaves. The seeds are have a dark blue, fleshy seed coat. The seed coat is covered with a whitish, waxy coating, making the seed appear light blue.

 
Similar
Species

May-apple (Podophyllum peltatum) leaves are not compound. The flower droops from the axil of two leaves. The fruit is a yellow berry.

Twinleaf (Jeffersonia diphylla) leaves are divided into 2 kidney-shaped segments. The flowers are borne on a leafless flower stalk. The fruit is brownish and capsule-like.


Distribution Distribution Map   Sources: 2, 3, 4, 5, 7, 28.

Comments

 


Taxonomy

Family:

Berberidaceae (barberry)

 

Subfamily:

Berberidoideae

 

Tribe:

Leonticeae

 
Synonyms

 

 
Common
Names

blue cohosh

papooseroot

papoose-root

squawroot

squaw-root


 

 

 

 

 

 

Glossary

biternate

Twice ternate. A leaf divided into 3 segments, with each segment divided into 3 leaflets.

 

bract

Modified leaf at the base of a flower stalk or flower cluster.

 

compound leaf

A leaf that is divided into leaflets, each leaflet having the general appearance of a leaf, with all leaflets attached to a single leaf stem.

 

nectary

A tissue or organ which produces nectar, usually at or near the base of the inside of a flower.

 

pedicel

In plants: the stalk of a single flower in a cluster of flowers. In Hymenoptera and Araneae: the narrow stalk connecting the thorax to the abdomen.

 

rhizome

A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.

 

sepal

An outer floral leaf, usually green but sometimes colored, at the base of a flower.

 

triternate

Three times ternate. A leaf divided into 3 main divisions, with each division divided into 3 segments, and each segment divided into 3 leaflets.

       

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Inflorescence

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Infructescence

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  Blue Cohosh (Caulophyllum thalictroides)
Andree Reno Sanborn
 
  Blue Cohosh (Caulophyllum thalictroides)  

 

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About

Published on Mar 24, 2012

Blue Cohosh

 
     
  An Herb Tip
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Published on Jul 23, 2013

Brett stops to talk about Blue Cohosh.

 
     

 

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