MACROSCOPIC—
The herb is an erect, coarse, rough-hairy perennial, usually up to 90 cm tall, rarely up to 180 cm. The leaves are alternate and simple; the lowermost leaves are slender, long, and petioled, ovate to broadly lanceolate, mostly penta-nerved, acute or acuminated at the apex, abruptly narrowed or rarely cordate at the base, usually sharply dentate, and 7 to 20 cm long and 2.5 to 7.5 cm wide; the petioles are mostly winged at the summit. The upper leaves are narrower, often almost entirely sessile, lanceolate or ovate lanceolate, and usually with 3 veins.
The flower heads are radiate, to 15 cm across, solitary or few, and long-peduncled, with 12 to 20 rays, purple, crimson, or rarely pale; the bristle disks are often orange, 3.5 to 7.5 cm long; the involucre is depressed-hemispheric; the bracts are lanceolate, spreading or appressed, imbricated in 2 to 4 series, and hairy on the outer surface with ciliate margins; the receptacle is conical, the scales of the receptacle stiff, spinescent, and conspicuously longer than the disc flowers; the chaff is carinate and cuspidate; the achenes are 3 to 4 mm in length, tetrasided, obypyramidal, and thick; the pappus has a short, dentate crown.
MICROSCOPIC—
Leaf—
The leaf has a thickness of 200 to 350 µm, with an epidermis 9 to 13 µm thick, largely without chloroplasts; the stomata are 28 to 35 µm, abundant on the dorsal surface and fewer on the ventral surface; the mesophyll is clearly divided into palisade parenchyma and sponge parenchyma. The palisade parenchyma is one layer thick, with elongated cells 50 to 65 µm in length, oriented at right angles to the leaf surface, containing numerous chloroplasts. The sponge parenchyma is 150 to 250 µm thick, with cells of irregular shape, and has multiple cell layers, few chloroplasts, and large intercellular spaces. The phloem bundles of the lateral veins within the sponge parenchyma are bound by a one-layer sheath of small parenchymous cells, with vascular elements of the midrib surrounded by large-celled parenchyma. The uniseriate trichomes are few in the ventral surface, numerous on the dorsal surface, typically tricelled, occasionally tetra- or pentacelled, 250 to 500 µm in length, each arising from an epidermal cell; the epidermal cell walls appear with moderate thickening; the vessels are various, scalariform, with variable reticulated width.
Petiole—
The parenchyma appear without chloroplasts, in several layers adjacent to a layer of collenchyma; 5 to 7 phloem bundles of small- to medium-sized vessels are weakly lignified and embedded in the parenchyma in the form of an arc; the wing ribs of the upper surface of the slightly hollowed petiole are marginal.
Inflorescence—
The epidermal cells of the ray florets are square, 50 µm, with a transparent, beaded cell wall; various elements of the asteraceous exhibit inflorescence; numerous multicellular jointed trichomes of the involucral bracts are 500 to 800 µm in length; tangential sections of the paleae with numerous fiber bundles are 10 to 15 µm in diameter and 100 to 150 µm in length; cell walls are thin. The epidermis of ray florets is reddish to violet; the epidermal cells from the end of the corolla form rounded papillae; a stigma of papillary cells is present; asteraceous pollen grains are 20 to 30 µm and spherical with a warty exine.
Calcium oxalate is negative; crystals of inulin and starch granules are rare.
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USP Chlorogenic Acid RS. USP Powdered Echinacea purpurea Extract RS. USP 2E,4E-Hexadienoic Acid Isobutylamide RS.
. The flow rate is about 1.5 mL per minute. The chromatograph is programmed as follows.