Perennials, 50-80 cm (fibrous-rooted and rhizomatous). Stems 1, erect, branched or unbranched distally, sparsely villous to glabrate. Leaves sessile; blades linear-lanceolate to oblong-lanceolate, 5-10 cm × 4-8 mm, (margins serrate to doubly serrate, teeth antrorse) faces sparingly villous or glabrate. Heads 10-25+, in crowded, simple or compound, corymbiform arrays. Phyllaries 20-30 in ± 3 series, (light green, margins light to dark brown, midribs dark green or yellow-green) lanceolate to oblanceolate, faces (abaxial) sparingly tomentose. Receptacles convex; paleae oblong, 3.5-4.5 mm (apices dark, rounded). Ray florets 6-8(-12), pistillate, fertile; corollas white, laminae 1-3 × 2-3 mm. Disc florets 25-30+; corollas grayish or yellowish white, 2-3 mm. Cypselae 2.5 mm. 2n = 36. Flowering early Jul-early Sep. Meadows, forest edges, roadsides, lakeshores, along streams, moist soils; 100-600 m; Alta., B.C., Man., N.W.T., Ont., Que., Sask., Yukon; Alaska, Minn., N.Dak.; Asia. Achillea alpina has been reported (as A. sibirica) as occurring in New Jersey and Missouri. Specimens examined from those states were from plants cultivated in botanical gardens; there is no evidence that Achillea alpina has escaped in those states.
Resembling no. 1 [Achillea ptarmica L.]; stems 5-8 dm; lvs 5-10 cm נ4-8 mm, incised; heads in a short, crowded, corymbiform infl; rays 6-13, 1-2 mm; disk-fls 25-30; 2n=36. Woods; ne. Asia to Man. and Minn.; Gasp顰eninsula, Que. July, Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.