Echinacea
purpurea (L.) Moench Standardized Common
Name: Echinacea purpurea
Other Common Names: Missouri Snakeroot,
Purple Coneflower
Family: Asteraceae
(Compositae)
Taxonomy: Echinacea
includes nine or four species of North American perennial herbs, depending upon
which treatment is accepted. Echinacea purpurea is defined identically
by either treatment, as it is quite distinct from other members of the genus,
being placed in its own subgenus by Binns et al. (2002). The basionym is Rudbeckia
purpurea L. A technical taxonomic problem with the application of the name E.
purpurea has been identified, but because of the economic importance of
this species, it is expected that the name will be formally conserved in order
to preserve its current meaning.
Description: Perennial herb with
fibrous roots; stems 50–80(–180) cm high, branching, usually pubescent on upper
portion. Leaves alternate, mostly petiolate; basal leaves long-petioled, ovate to
lanceolate, (5–)15–22(–30) cm long, (1–)5–10(–15) cm broad; stem leaves
narrowly to broadly lanceolate or rarely ovate, (4–)11–17(–24) cm long,
(1–)2–7(–11) cm broad, the upper leaves sessile; base rounded to tapering,
cordate, or rounded and abruptly tapering at petiole, sometimes asymmetrical,
the petiole of cauline leaves sometimes appressed to the stem; apex acute;
margins usually serrate to dentate or undulate; main veins branching, 3 (or 1
or 5); both surfaces, especially the upper, pubescent with short 2-celled
stalked hairs. Inflorescence a capitulum (head); receptacle 1.5–3.0(–3.5) cm
high, conical to hemispherical or flattened; involucral bracts (phyllaries) in
4 series, (8–)10–15(–20) mm long, green, usually recurved, usually pubescent on
outer surface; receptacular bracts (paleae) 9–13(–15) mm long, reddish,
straight-awned; awn golden with red or orange tip. Ray florets ligulate,
usually sterile, (2.5–)3.5–5.0(–6.0) cm long, (3–)5–13(–19) mm broad, dark pink
to purple or rarely pinkish white, parallel to stem or reflexed to spreading,
pubescent at least on outer surface. Disk florets symmetrical, tubular; corolla
tube 4.5–5.5 mm long, 5-lobed; corolla lobes usually green and pink, rarely
purple or orange, with stalked or sessile trichomes; anthers 5; style
2-branched, usually purple, rarely pale. Fruit a cypsela, 3–6 mm long; pappus
of 4 equal teeth in disk florets (3-toothed in ray florets), or of 1 large
tooth, or rarely absent.
Parts
in Commerce:
Whole herb (small stems, leaves and flowers, avoiding large stems), usually
fresh, and/or roots, often with rhizome; fruits (“seeds”) also sometimes used
Identification:
Whole
herb
- Stems variable
in color, longitudinally ridged or striated, in upper portion of plant
often pubescent with short stiff hairs; whole stems branching
- Leaves
lanceolate to broadly ovate, quite variable in size, the larger leaves
usually ovate and >5 cm broad
- Larger basal
leaves long-petioled; uppermost stem leaves sessile
- Leaf base
rounded to cordate in large leaves, sometimes with acutely tapering
extension of blade down petiole, or rounded to tapering in small leaves
- Leaf apex acute
to narrowly acute
- Leaf margins
toothed in all but the smallest leaves, with at least a few shallow,
widely spaced teeth
- Main leaf veins
3 or 5 (rarely 1 in small leaves), with branching secondary veins
- Both leaf
surfaces bearing short stiff 2-celled hairs, feeling rough especially when
stroked toward base
- Heads terminal,
the receptacle conical to ovoid or hemispherical, rarely flat-topped at
maturity, often flattened in early flowering
- Receptacular
bracts (phyllaries) at base of head in usually 4 overlapping whorls, often
recurved, usually pubescent at least on margins
- Ray florets
purple to pink or rarely whitish, in 1 series, usually reflexed or parallel
to stem, occasionally spreading outward
- Ray florets
(2.5–)3.5–5.0(–6.0) cm long, mostly over 5 mm broad, with 2- or rarely
3-toothed apex, pubescent on outer surface with short inconspicuous hairs
- Stiff awned
receptacular bracts (paleae) subtending individual disk florets longer
than disk florets; awn tip straight, reddish or orange
- Mature fruit
(3–)4.5–5.5(–6.0) mm long, without colored striations, with pappus usually
of 4 teeth at apex (or 3 teeth in fertile ray florets), rarely of 1 large
tooth or absent
- Odor weak,
aromatic
- Taste weak,
initially sweetish, then slightly bitter
Roots
- Rhizome shorter
than roots, irregularly shaped and wrinkled, usually 5–10 mm thick
- Roots fibrous,
numerous, to 15 cm long, 1–3 mm thick, deeply longitudinally wrinkled when
dry, sometimes spirally twisted
- Rhizome and
roots light or reddish brown to dark brown or black
- Root tough when
fresh, fibrous when dried
- Root in
cross-section shows very thin cork or epidermis; ring of cortex
(containing orangish resin canals); large vascular tissue with xylem in a
few broad wedges containing strands of parenchyma, separated by distinct
parenchyma rays or forming a nearly solid cylinder; very small area of
central parenchyma
- Rhizome hard;
fracture tough, externally fibrous
- Rhizome in
cross-section shows very thin cork; narrow cortex (containing stone cells
surrounded by black pigment); dense ring of xylem; large cream-colored
pith (containing orangish resin canals and stone cells surrounded by black
pigment)
- Odor weak,
aromatic and acrid, characteristic
- Taste weak,
initially sweet, then bitter, causing a tingling sensation and salivation
when chewed
Adulterants: Roots of Parthenium
integrifolium L. (legitimately sold as Prairie Dock) have repeatedly been
sold as E. purpurea. Both are members of the aster family and are
sometimes called Missouri Snakeroot, which may have been the historical cause
of substitution. However, the two are easily distinguished, and any such
substitution at the present time can only be attributed to deliberate fraud.
Several characters distinguish P. integrifolium, including:
- Outer surface
black (occasionally seen in E. purpurea also)
- Irregularly
shaped taproot with several tapering branches emerging from lower surface;
taproot and main branches >3 mm thick
- Black pigment
present in roots; in cross-section, at least one ring of small black spots
can be seen near outside of root
- Xylem in
numerous narrow radial wedges
- Large taproots
have vascular tissue that contains several rings of parenchyma
interspersed with pigment deposits, giving the appearance of concentric
circles of light and dark spots
- Taste bitter,
not causing tingling or salivation
Other species of Echinacea
have traditional uses as well. Current commercial practice favors using only
the taproots of E. angustifolia DC. and E. pallida
(Nutt.) Nutt. (cf.), which are easily distinguished from the roots of E.
purpurea if examined before excessive processing has occured. Aboveground
parts from these and related species are likewise easily distinguished by their
narrow leaves with unbranched veins and entire leaf margins (see illustration
in the treatment of those species).
Echinacea laevigata (C. L. Boynton &
Beadle) S. F. Blake, which is an uncommon southeastern species, is probably the
species most easily confused with E. purpurea in the field as its leaves
are up to 6 cm broad with serrate margins. It may be distinguished by several
features:
- Leaves glabrous,
not rough, with unbranched main veins and with nearly entire margins above
- Involucral
bracts (phyllaries) in 1–3 series and usually lacking stalked hairs
- Ray florets as
long as in E. purpurea, but usually only 3–5 mm broad
- Receptacular
bracts (paleas) with frequently incurved rather than straight awns
- Fruits usually
have horizontal colored striations and a pappus of 1 large tooth
References:
Binns SE, Baum BR, Arnason JT. Typification of Echinacea
purpurea (L.) Moench (Heliantheae: Asteraceae) and its implications
for the correct naming of two Echinacea taxa. Taxon.
2001;50:1169–1175.
Binns SE, Baum BR, Arnason JT. A taxonomic revision
of Echinacea (Asteraceae: Heliantheae). Syst Bot.
2002;27:610–632.
McGregor RL. The taxonomy of the genus Echinacea
(Compositae). Univ Kansas Sci Bull. 1968;68:113–142.
Upton, R., ed. Echinacea purpurea Root.
Echinacea purpurea (L.) Moench. Standards of Analysis, Quality Control, and
Therapeutics. Scotts Valley, CA: American Herbal Pharmacopoeia; 2004.
Wichtl M, ed. Herbal Drugs and
Phytopharmaceuticals, 3rd English
ed. Stuttgart: medpharm Scientific Publishers and Boca Raton, FL: CRC Press;
2004:185.
Figure 23: a–e, Echinacea purpurea head, disc floret,
leaf, leaf close-up and root cross-section.
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