Stems mostly solitary, 2-5 dm from a long, nearly naked rhizome, spreading-villous and often glandular above, mostly glabrous below; lvs sparsely long-hairy or subglabrous, dentate or denticulate, the lower ones evidently petiolate, elliptic or oblanceolate, to 20 cm (petiole included) נ4 cm, the upper sessile and often more lance-ovate or lance-oblong, the stem appearing leafy; heads 1-3, campanulate, the disk 1.5-2 cm wide; invol 10-13 mm, spreading villous and stipitate- glandular, the bracts more strongly acuminate than in no. 1 [Arnica lonchophylla Greene]; rays 10-15, 1.5-2 cm; pappus-bristles tawny, subplumose; 2n=76 (apomictic tetraploid). Streambanks and other moist, protected places especially in acid soils; mts. of n. N.Y., N.H., and Me. to N.B. and the Gasp顰enins. of Que. July, Aug. (A. mollis, misapplied)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.