Rhizomatous, 1.5-6 dm; stem glabrous below, usually hairy in lines above; lvs glabrous, entire or shallowly toothed, linear or lance-linear to lance-elliptic, the basal petiolate, the others sessile or nearly so, 3-10 cm נ3-10 mm, the upper reduced and mostly rather few; heads relatively few in an elongate, open infl; invol 3.5-5 mm high, glabrous, its narrow bracts well imbricate, with ±elongate green tip; rays 15-30, 3-8 mm, white; lobes of the disk-cors comprising 30-45% of the limb; 2n=16, 32. Seasonally inundated streambanks and shores, often among rocks; s. Que., s. N.S. and c. Me. to N.Y. and the Delaware R. in N.J.; n. Mich.? (A. saxatilis)

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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