Boreal Yarrow

Achillea borealis Bong. Mdm. Acad. St.-Petersb. VI. 2: 149 1832.
Ptarmica borealis DC. Prodr. 6: 21. 1837.
Achillea Millefolium occidentalis Ledeb. Fl. Ross. 2 : 532. 1S46. Not A . Millefolium occidentalis DC.
1837. Achillea anethifolia Fisch.; Herder, Bull. Soc. Nat. Mosc. 38: 404, as synonym. 1865.
A perennial, with a rootstock; stem 3-8 dm. high, striate or grooved, sparingly longvillous; leaves bior tri-pinnatifid, sparingly villous, the lower petioled, often 2-3 dm. long, 2-6 cm. wide; upper leaves sessile, lanceolate with a broad base, 1-2 cm. wide; primary divisions ovate in outline, spreading; ultimate divisions linear, spinulose-mucronate; heads numerous, in more or less compound corymbiform panicles; involucre fully 5 mm. high and 4 mm. broad; bracts 20-25, ovate or ovate-lanceolate, all acute, the outer ones half as long as the innermost; margins dark-brown or nearly black; ray-flowers 5 or 6; ligules white or pink, 3-4 mm. long, nearly orbicular, roimd-lobed ; disk-flowers 20-25; corollas yellowishwhite, 3 mm. long, glandulargranuliferous; achenes nearly 3 mm. long, strongly wing-margined.
Type locality: Island of Sitka, Alaska.
Distribution: Vancouver Island to Alaska and Yellowstone Park; California (?); also i,i eastern Siberia.