Perennials, 5-35 cm; rhizomatous, fibrous-rooted, caudices sometimes branched. Stems erect, sparsely and loosely strigose to strigoso-villous, eglandular. Leaves: basal and proximal cauline much reduced or present as scales; cauline blades linear to linear-oblong or oblong-lanceolate, 10-30 × 1-5 mm, largest at midstem, then relatively even-sized to peduncles, margins entire, sometimes prominently ciliate, faces glabrous or sparsely villous. Heads 1(-5). Involucres 4-6 × 6-12 mm. Phyllaries in 2-3 series, loosely and sparsely strigose, eglandular. Ray florets 20-50; corollas white, less commonly pinkish, or aging pinkish, 4-8 mm, laminae not coiling or reflexing. Disc corollas 3-4.6 mm. Cypselae 1.3-1.6 mm, 5-6-nerved, faces glabrous; pappi: outer of setae, inner of 25-35 bristles. 2n = 18. Flowering Jun-Aug. Open woods, river gravel, rock ledges and crevices, gravel barrens, roadsides; 0-500 m; Alta., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Maine, Mich., N.H., N.Y., Vt. Variety villicaulis, from Anticosti Island (Quebec) and Newfoundland, has been distinguished on the basis of its relatively shorter stature (mostly 3-15 cm) and greater ratio of peduncle to leafy-stem lengths (stems and peduncles as long as or longer than the leafy parts of stems); the distinction appears to be arbitrary.
Perennial; stems numerous, 15-35 cm, subglabrous or sparsely strigose to occasionally densely spreading-villous; lvs thin, lax, subglabrous, all about alike except for the reduced and scale-like lowest ones, linear or nearly so, to 3 cm נ5 mm, often with short leafy axillary shoots; heads 1-5, on conspicuous, long, subnaked peduncles to which the cauline lvs are abruptly reduced; disk 6-12 mm wide; invol 4-6 mm; rays 20-50, white or sometimes pink or rose- purple, 4-8 mm; pappus obscurely double; 2n=18. Mostly on rocky shores and banks; n. Vt. to Me., se. Can., and n. Mack. Summer. Ours is var. hyssopifolius.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.