Actaea
racemosa L.
Standardized Common Name: Black Cohosh
Other Common Names: Black Snakeroot, Bugbane, Macrotys, Rattleroot, Rattleweed
Family: Ranunculaceae
Taxonomy: Actaea is native to North America and Eurasia, especially east Asia. It has been divided into two genera: Cimicifuga included about two dozen species with dry fruits, while Actaea included about eight species with fleshy fruits. Black cohosh belongs to the former group and is most commonly known as Cimicifuga racemosa (L.) Nutt. However, the close resemblance between Cimicifuga and Actaea, as well as molecular evidence that the latter genus arises from the former, justifies recombining the two, and Actaeaas the older name has priority. About a dozen synonyms exist, of which several may be encountered in older literature, including A. monogyna Walt., Botrophis serpentaria Raf., Cimicifuga serpentaria Pursh, Macrotrys actaeoides Raf., Macrotys [sic] racemosa Sweet, and M. serpentaria Eaton.
Description: Rhizomatous perennial herb. Rhizome horizontal, large; upper side with upturned buds and rounded stem and petiole scars, lower side with long slender roots. Leaves mostly basal, 2–3-ternately or ternate-pinnately compound, often over 0.5 m wide; lateral leaflets ovate to obovate, 4–12 cm long; terminal leaflets 3-lobed with 3 basal veins, to 15 cm long, breadth often equaling or exceeding length; bases cuneate to shallowly cordate; apices acute; margins dentate to serrate; surface dark green, glabrous or nearly so. Inflorescence on peduncle to 2 m high, with (2–)4–9 racemose branches; branches 10–60 cm long, many-flowered. Flowers white; sepals 4(–5), quickly lost; petals variable in number, ca. 3 mm long; stamens numerous, white, showy, 5–10 mm long; gynoecium of 1 carpel. Fruit a follicle, 5–10 mm long, ovoid, slightly flattened; seeds 8–10.
Parts in Commerce: Rhizome with roots
Identification:
- Rhizome large,
clumpy; to 15 cm long, 1–2 cm broad when dried
- Upper surface
packed with short branches bearing undeveloped buds or cup-shaped leaf and
stem scars, about 1 cm thick
- Lower surface
bearing many long narrow roots; when dried, roots are brittle and easily
break off
- Surface dark
brown, with bud scale scars in the shape of incomplete rings around
branches
- Young buds
pinkish white
- Fresh rhizomes
whitish inside, turning pink and later grayish upon immersion in ethanol,
darkening upon exposure to air; when dried, non-vascular tissues turn
dark, vascular bundles remain pale
- Fracture very
hard
- Rhizome oval to almost
round in cross-section: shows thin cork layer; numerous long narrow
vascular bundles usually extending most of the distance between cork and
pith, separated by broader rays; and large central pith
- Roots 8–20+ cm
long, 1–2.5 mm in diameter (rarely reported to reach 5 mm in diameter),
brittle and easily broken when dried
- Root when fresh
circular in cross-section, showing central vascular cylinder 0.8–1.3 mm in
diameter with (2–)3–4(–6) thick wedge-shaped xylem bundles in all but the
smallest roots
- When dried,
larger roots may appear angular in cross-section due to shrinkage of
tissues around the conspicuous xylem bundles
Cultivated
specimens of A. racemosa with very different gross rhizome morphology
have been observed; in this form, the rhizome is up to 0.5 m long, straight and
cylindrical, with several cm between branches; bud-bearing branches are
likewise longer and extended outward from the main rhizome. While these plants
may be genetically unusual, it is reasonable to suppose that plants cultivated
under shade in loose soil will in general grow more expansively than
wildcrafted plants that grew in rocky soil filled with tree roots. The
cross-section of the rhizome and root should be similar.
Adulterants: Several related
species are potential substitutes. The general form of the vascular tissue of
the rhizome can be observed with the naked eye or a hand lens in fractured
material, and that of the roots with a hand lens or dissecting scope.
A.
pachypoda
Elliott
- Range
overlapping that of A. racemosa
- Plant smaller
than A. racemosa; rhizome <1 cm thick, with fewer stem scars
- Vascular bundles
of rhizome few, irregularly spaced, usually <1 mm long
- Roots <2 mm
in diameter when dried; vascular cylinder about 0.5 mm in diameter
- Wedges of
secondary xylem in roots absent or inconspicuous
A.
podocarpa
DC. (C. americana Michx)
- Range very
limited
- Vascular bundles
irregularly spaced near outside of rhizome, rounded rather than elongated
(length usually less than twice width)
- When dried,
fractured rhizome has darkened pith often with an irregular yellow area in
center, which is rare in A. racemosa
- Vascular tissue
of root smaller and less developed; wedges of secondary xylem absent or
inconspicuous
A.
rubra
(Aiton) Willd.
- Native to
Western United States
- Rhizome over 1
cm thick, with conspicuous ring of often broad vascular bundles; large
triangular fiber bundles may be seen outside the vascular tissue if
material is stained
- Roots thick, up
to 5 mm in diameter; cortex narrow, vascular cylinder occupying most of
root
- Root xylem
consists of 3 very large, conspicuous wedges
A.
cimicifuga
L. (C. foetida L., including A. simplex (DC.) Wormsk. ex Prantl)
- Most commonly
employed Asian species, sold with two other species as Chineae Cimicifuga,
may be mistakenly cultivated under the name of A. racemosa in North
America
- Vascular bundles
widely spaced, very narrow, often <1 mm long
- Root vascular
cylinder smaller and less developed, with secondary xylem wedges absent or
inconspicuous
References:
Applequist WL. Rhizome and root anatomy of potential
contaminants of Actaea racemosa L. (black cohosh). Flora.
2003;198:358–365.
Compton JA, Culham A, Jury SL. Reclassification of Actaea
to include Cimicifuga and Souliea (Ranunculaceae):
phylogeny inferred from morphology, nrDNA ITS, and cpDNA trnL-F sequence
variation. Taxon. 1998;47:593–634.
Lloyd JU, Lloyd CG. Drugs and Medicines of North
America. Cincinnati, OH: Robert Clarke & Co.; 1884–85. [Reprinted in Bull
Lloyd Lib. 1931;30.]
Radford AE, Ahles HE, Bell CR. Manual of the
Vascular Flora of the Carolinas. Chapel Hill, NC: University of North
Carolina Press; 1968.
Ramsey GW. Morphological considerations in North
American Cimicifuga. Castanea. 1987;52:129–141.
Ramsey GW. Cimicifuga. In: Flora of North
America Editorial Committee, eds. Flora of North America, vol. 3. New
York, NY: Oxford University Press; 1997:177–181.