Plants 5-25 cm; taproots short, thick, tuberous. Stems decumbent to erect, mottled purple, simple, glabrous proximally, tomentulose distally. Leaves: proximal present at flowering; petiolate (petioles 2-8 cm, not winged); blades ovate to deltate, 2-8 × 0.5-3 cm, bases hastate or sagittate, margins entire or weakly dentate, faces glabrous; distal reduced, elliptic to lanceolate. Heads (10-20) in narrow, racemiform to thyrsiform arrays (nodding). Calyculi of 4-5, dark green to blackish, subulate bractlets 2-5 mm, glabrous. Involucres cylindro-campanulate, 10-11 × 5-6 mm. Phyllaries 8-11, dark green to almost black, lanceolate to subulate, 8-12 mm, faces glabrous. Florets 9-20; corollas white, 7-13 mm. Cypselae light tan to yellow, subcylindric, subterete to angled, 5-6 mm, indistinctly 7-10-ribbed; pappi pale yellow, 6-8 mm. 2n = 32.

Flowering Jul-Aug. Alpine areas above treeline, mountains; of conservation concern; 1500-2000 m; Maine, N.H., N.Y., Vt.

Prenanthes boottii is recognized by its relatively short, decumbent habit, deltate to hastate proximal leaves, entire or weakly dentate margins, glabrous and blackish green phyllaries, white corollas, and alpine habitat.

Stem 1-3(-4) dm, glabrous below, villous- puberulent above, at least in the infl; lvs glabrous, pale beneath, entire or merely toothed, the lower with deltoid or cordate blade 1.5-5 נ1-3 cm, exceeded by the petiole; infl narrow, somewhat thyrsoid; heads mostly nodding; invol 8-12 mm, black or blackish-green, the pigment-spots minute, crowded, generally resolvable into short parallel lines at 50׻ principal bracts 8-11(-13), minutely puberulent at the tip, otherwise glabrous; some of the reduced outer bracts generally at least half as long as the main ones; fls 9-18, whitish; achenes evidently several-ribbed, but only obscurely striate; 2n=32. Alpine sites; n. N.Y. to Me. July, Aug.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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