Description from Flora of China
Achillea millefolium Linnaeus var. setacea (Waldstein & Kitaibel) W. D. J. Koch.
Herbs, perennial, 30-70 cm tall, with procumbent slender rhizomes; stems erect, unbranched or few branched in upper part, usually with short sterile branches at leaf axils above middle, white villous, especially in lower part. Basal leaves petiolate; leaf blade linear-lanceolate, rarely linear-oblong, 8-20 × 1-2 cm, (2 or)3-pinnatisect, both surfaces villous; primary segments many, 1-1.5 mm apart; ultimate segments filiform-linear or linear-lanceolate to lanceolate, 0.5-1.5 × 0.1-0.2 mm, apex cartilaginous-mucronulate; middle and upper stem leaves similar, sessile, gradually smaller. Synflorescence a terminal flat-topped panicle, 2.5-7 cm in diam. Capitula many. Involucres narrowly oblong or ovoid-oblong, 4-4.5 × 2-2.5 mm; phyllaries in 3 rows, yellowish green, midvein greenish, convex, abaxially brownish pilose, oblong-ovate to oblong, 2-4 × 0.8-1.2 mm, scarious margin sometimes with narrow pale brown edge, apex somewhat acute or obtuse. Paleae oblong-lanceolate to lanceolate, glabrous or appressed pilose on upper part. Ray florets 5; lamina yellowish white, semiorbicular or suborbicular, 1.2-1.3 × 1.3-1.8 mm, apex subtruncate or 3-dentate. Disk florets yellow, tubular, 5-lobed. Achenes oblong-cuneate, 1.8-2 × ca. 0.8 mm, with narrow lateral ribs. Corona absent. Fl. and fr. Jul-Aug. 2n = 18, 36.
Wastelands, forest margins, grasslands on mountain slopes, meadows, river valleys; 500-2400 m. Heilongjiang, Xinjiang [Kazakhstan, Mongolia, Russia; N Africa, SW Asia, Europe].