Achillea setacea Waldst. & Kit.

Rare in our area in loamy-clay soils in forest zone. It is cultivated as an ornamental and may be the specimen cited above is an escape.

Erect to ascending erect, up to 80 cm tall, usually unbranched, white villose-stemmed herb. Leaves linear to linear-lanceolate, 3 – 8 (-10) cm long, up to 2 cm wide, (2-) 3-pinnatisect into filiform-linear or linear-lanceolate, 0.5–1.5 x 0.1–0.3 mm, cartilaginous mucronulate, setaceous, often congested ultimate segments, basal and lower leaves on up to 5 cm long petioles, middle and upper stem leaves sessile and gradually smaller, rachis 0.4 – 0.6 mm wide. Capitula oblong, 40–150 or more, 2.5–3 mm across, on up to c. 3 mm long peduncles, in dense, up to 8 cm broad compound corymbs. Involucre oblong to oblong-cylindric, 3.5–4.5 x 2–3 mm, shortly attenuate and sparse to dense pilose below, phyllaries 3-seriate, oblong-ovate to oblong-lanceolate, outer pale, brownish at the acute tips, inner apically obtuse and scarious. Paleae oblong-lanceolate to lanceolate, whitish-membranous, glabrous to hairy towards the acute apices. Ray-florets 4-5, with inconspicuously 3-lobed, ± orbiculate, 1–1.2 x 1–2 mm, white ligules. Disc-florets 10–20, with yellow, 5-lobed corolla tube. Cypselas oblong-cuneate, 1.8 – 2 mm long, laterally ribbed, light brown.

Distribution: South, Central and Eastern Europe eastwards to China through Russia and Central Asia; introduced and cultivated in many parts of the world.

Fl. Per.: July-August.

A. millefolium L. var. setacea (Waldst. & Kit.) W. D. Koch, Syn. Fl. Germ. 373. 1837; A. fililoba Freyn, Fl. 1881: 210. 1881; A. setacea Waldst. & Kit., var. filifolia Boiss., Fl. Or. Suppl. 295. 1888.

Achillea setacea Waldst. & Kit. PI. Rar. Hung. 1: 82. 1802
A perennial, with a creeping slender rootstock; stem 2-4 dm. high, striate, green, sparingly silkyvillous, decumbent at the base; leaves twice pinnatifid, green, sparingly pubescent, the lower 1-1.5 dm. long, narrowly oblanceolate, petioled, the upper linear, sessile, 5-8 cm. long; rachis margined; primary di-isions obovate in outline, spreading, the ultimate ones linear, spinulose-tipped; heads in open corymbiform panicles; involucre campanulate, 3-4 mm. high ; bracts 1 8-20, in 4 series, elliptic, obtuse, the midrib prominent, straw-colored, bordered by light-green on both sides ; margins straw-colored ; ray-flowers 4 or 5 ; ligules white, less than 2 mm. long, suborbicular; disk-flowers 10-15; corollas yellowish-white.
Type locality: Near Pest, Hungary.
Distribution: Edgartown, Massachusetts, and Saguinay County, Quebec; adventive from Europe.