An erect, often robust, sparingly branched perennial herb to, c. 3 m tall from a large woody rootstock. Stems annual, solitary or several clustered, simple below, uniformly leafy, striately ribbed, puberulous to pilose-tomentose, glabrescent; synflorescence branches stiffly ascending or somewhat laxly spreading, up to c. 30 cm long. Leaves subsessile on the upper stem, or with a petiole up to c. 10 mm long on the lower stem; lamina 3-18 x 0.6-5 cm., oblong-elliptic to oblanceolate, lanceolate in uppermost leaves, apices rounded-obtuse to acute, bases rounded to subcordate or broadly cuneate, margins ± coarsely serrate, puberulous to glabrescent, sometimes hispid on the main veins beneath and then scabridulous. Capitula numerous, in few to many dense clusters terminal on branches, or capitula in a large ± lax terminal paniculate arrangement; capitula stalks mostly 0.2-3 cm long, often bracteate; bracts up to c. 4 mm long, scale-like and merging into the phyllaries; synflorescence branches with narrowly-oblong leaves up to c. 5 cm long. Involucres 7-15 x 5-15 mm, narrowly cylindric-campanulate to broadly obconic-campanulate, glabrous or hispidulous. Phyllaries usually somewhat differentiated apically, progressively longer to the inside, greenish-stramineous, stiffly coriaceous, hispidulous to pubescent or glabrescent; apices puberulous, glandular, dark-green or purplish, sometimes somewhat expanded; margins pectinate-denticulate or pungent-ciliolate; the outer phyllaries from c. 2 mm long, ovate to linear-lanceolate; the inner phyllaries to c. 14 mm long, linear-lanceolate to narrowly oblong-lanceolate, acute or obtuse-mucronate. Receptacle fimbriate-alveolate. Corollas blue, up to c. 14 mm long, narrowly tubular with a deeply lobed limb. Achenes dark-brown when mature, 5-7 mm long, narrowly subcylindrical to subfusiform, c. 10-ribbed, strigose-bispid; outer pappus of short, irregular, 0.5-2 mm long, narrow, scale-like setae, inner pappus of brown-purplish, somewhat flattened, subplumose setae 8-10 mm long.
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Lax, low-growing, less robust plants; involucre mostly less than 10 mm long; capitula laxly arranged usually on long stalks, not densely clustered; or capitula in small clusters laxly paniculately arranged; outer phyllaries relatively fewer, ovate-lanceolate, seldom extending onto capitulum stalk.
Perennial herb, up to 1 m high. Heads laxly arranged, usually on long stalks, not densely clustered, or heads in small clusters laxly paniculately arranged. Involucre mostly shorter than 10 mm, outer involucral bracts fewer, ovate-lanceolate, seldom extending onto stalk of head. Flowers blue.
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