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.