Caulophyllum thalictroides (L.) Michx.
Researcher: Tanner Filyaw

Common Names:
Blue Cohosh
Blueberry root
Papoose root
Squawroot
Blue Ginseng,
Yellow Ginseng

Genus: Caulophyllum, contains 5 species,
with 2 in North America, and the other 3 being native to Asia (8).

Family: Berberidaceae, conatins 10 genera (14)

Synonyms: Leontice (18)

Relatives: Caulophyllum giganteum (Farw.) Loconte & Blackwell (14) can be distinguished
from C. thalictroides by its purple flowers, 
but for most purposes they are treated as the
same plant (10).
Caulophyllum robustum is an Asian relative
of C. thalictroides

Duration: Perennial (14)

Habit: Erect forb/herb (14)

Height: Reaches and average height of
1-2 feet (21), but rarely reaches more than 3 feet (19).

Stems: Stems are smooth, purplish in color, and forked (14), with the aerial shoots
emerging in the second spring following germination (4).


Blue Cohosh Leaves ©Rural Action
Stock Photo

Leaves: The leaves of C. thalictroides are compound, with the leaves on the upper
portion of the plant having fewer leaflets than
those on the bottom portion (16).  Each
leaf has between 3-5 leaflets, which are 1-3 inches long (16), and haS a forked
appearance with 2-3 lobes at the end (7).  The leaves are purple in color when they first emerge in the spring, and become bluish/green as the plant matures (4).  According to Adams (1927) the first leaves to emerge in the spring are true leaves, exhibiting what is known as hypogeal germination, where the cotyledons remain beneath the leaf litter on
the forest floor (1).


Merel R. Black, and
Wisconsin State Herbarium

Flowers: The flowers of C. thalictroides
are small, and roughly measure ½ inch across (21).  Flowers can be described as star-shaped, and are typically brownish-green to yellow in color (4).  They are arranged in a panicle that extends above the plant, with only one inflorescence per shoot (4). 
The flowers are perfect, with six
stamens arranged around a central pistil (16). 
C. thalictroides is considered one of the
earliest flowering plants in deciduous forests, and
typically blooms from April to June (10).

Fruit: The fruit of C. thalictroides is a
short-lived capsule containing either one
 or two seeds.  The fruit is short lived in the
sense that during the initial stages of seed development the capsule is ruptured, and
shed, with the seed completing its development outside of the ovule on an enlarged funiculus (10).  Arguments have been made that Blue Cohosh does not have a true fruit, since the ovarian wall is shed during the beginning stages of seed development, and instead referred
to as a “naked” seed.



caulopyllum seed - Keir Morse copyright 1996-2005
http://www.keiriosity.com/berberidaceae/caulophyllum_thalictroides01.htm

Seed:  Blue cohosh seeds closely resemble blueberries in appearance, but are poisonous
to humans (21).  The seeds are about the
size of a pea, and measure nine millimeters in diameter (4). Externally, the seeds are surrounded by a dark
blue fleshy seed coat, with the chocolate brown/mahogany seed on the inside, and have
two distinguishing dimples (4). The seeds mature
in mid-late August after their 5th year, and are dispersed by either gravity or wildlife (4).  The fleshy seed coat, which contains germination inhibiting compounds, is readily dissolved
whenit comes in contact with the soil, or has been passed through an animal’s digestive
tract (4).  These seeds are quite hardy, exhibiting resistance to bacteria, fungi, and rotting, which allows them to remain viable as long as they can remain moist (4).
Blue cohosh exhibits a unique two phase germination process that is lengthy, but will ultimately help ensure the survival of young seedlings.  Prior to germination, the seeds
must be stratified by going through four alternating periods of warm and cold temperatures, and
should finally germinate in their second spring (4). During the first phase of germination the root system begins to develop, as it spreads beneath the leaf litter, eventually setting a dormant bud for the next year (4).  The following spring marks the beginning of the second phase of germination,
and the above ground portions of the plant finally emerge.  According to Cech (2002)
Blue Cohosh can also experience double dormancy, where germination can take as
long as 889 days (4). 
By dividing germination into two separate phases, the seedling has a much better chance of survival because the root system is fully developed when
the aerial portions of the plant emerge.



http://www.horizonherbs.com/images/products/
blue-cohosh-Caulophyllum-thalictroides-root-small.jpg

Roots: The rhizome of C. thalictroides
can be described as a hard, thick, knotty
mass, roughly the size of a finger, with golden brown fibrous
roots radiating out in all directions (15).
Externally it is yellowish/brown in color,
and has several scars on the upper surface where stems were once attached (4). 
The root terminates in a dormant bud, curving up from the base, from which a new stem will emerge the following year (4). The root of this species has become adapted to moist environments, and is rot resistant (4).

Pollination: Bees and flies have been found to be the primary pollinators of blue cohosh (15).   During a study conducted in 1996, Hannan observed visitors of C. thalictroides, as well as C. giganteum, and found that 77% of those visitors were Dipterans (Flies) (10).  By nature, flies usually only visit single flowers, which results in decreased levels of pollen transfer (10).  This could be a reason why blue cohosh is not a major contributor to the soil seed bank.  When investigating colonization dynamics, Beatty (1991), found that blue cohosh seed was not abundant in the seed bank, even when it was found growing on site (2).

Habitat: Blue cohosh typically inhabits moist woodland areas, with mixed hardwood vegetation, and a complete forest canopy (4).  Sometimes this species can also be found in low-lying areas in close proximity to running streams (15), indicating that preferred sites do not necessarily have to be well drained (14).  Slightly acidic forest loam soils are indicative of these sites, with pH values between 5 and 6.  Blue cohosh will tolerate soils with higher percents of sand and clay, but sufficient organic matter, and surface mulch must be present (4).  Research indicates that canopy cover is an essential aspect of cohosh habitat.  When studying the reproductive biology of C. thalictroides, and C. giganteum, Hannan (1996) found that in the presence of excessive sunlight the anthers of Caulophyllum will dehisce, severely decreasing the amount of pollen available for fertilization and reproduction (10).

Associations: (3)(4)
Goldenseal (Hydrastis candensis)
Jack in the Pulpit (Arisaema triphyllum)
Ramps (Allium tricoccum)
Solomons Seal (Polygonatum biflorum)
Stoneroot (Collinsonia canadensis) 
Magnolia (Magnolia acuminata)
Basswood (Tillia heterophylla) 
Sugar Maple (Acer saccharum)
Hickory (Carya cordiformus)
Hemlock (Tsuga canadensis)
Beech (Fagus grandifolia)

Range: C. thalictroides is native to North America, hardy from zones three to eight (14), and can be found growing from New Brunswick to South Carolina, and just West of the Mississippi Valley. The greatest concentrations of Blue cohosh are found in New England, and the Allegheny region (4).

Pests and Diseases:  There are several documented diseases of C. thalicktroides. The species name is listed in italics, and the states where the diseases have been documented are listed in parentheses: (5)

Leaf Blight:
-Botrytis (NY, NJ)

Leaf Spot:
-Cercospora caulophylli (VT-VA, IA, MO, MS, WI, Canada)
 - Colletotrichum dematium (IL)
 - Vermicularia hysteriformis (WI)
 - Drechstera gigantea (IL, WI)
 - Phoma caulophylli  (Canada)
 - Phyllosticta sp (WI)

Powdery Mildew:
-Erysiphe cichoraceaum (Canada)

Root Blight:
-Cylindrocephalum sp. (WI)

Stem Blight:
-Calloria caulophylli (NY)
- Streptotinia caulophylli (Canada)
- Orbilia caulophylli

Other threats: Populations of C. thalictroides are also threatened by increased pressure from wild harvesting (7).

Conservation status: Aside from cultivating blue cohosh, little has been done along the lines of conservation.  It is interesting to note that this species has its own conservation strategy; since it prefers to grow in isolated and remote areas of the mountains that are poorly suited for development and growth (4).  Although many growers are attempting to sustainably cultivate C. thalictroides, the slow growing nature, and complex germination habits of the species are making things difficult (4).

History: Native Americans, and early European settlers used blue cohosh to address a wide range of maladies.  Native Americans found that cohosh tea stimulated contractions in the uterus, and therefore induced childbirth (20).  This practice became so common that the U.S. Pharmacopoeia officially listed the plant as a labor inducer from 1882 to 1905 (17).  Cohosh was also used in the treatment of irregular menstruation, menstrual cramps, and labor pains (20).  The plants use in treating feminine ailments is most likely how the species received the common name Squaw Root (20).  Aside from treating female maladies, Native Americans and early settlers used C. thalictroides to treat sore throats, bronchitis, rheumatism, anxiety, and colic (20).  Cohosh root was even boiled to produce an insecticide, and was applied to agricultural crops (6).