This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Herbs, mostly perennial, with erect leafy stems, finely dissected, pinnatifid or serrate alternate leaves, and small heads of both tubular and radiate flowers, corymbose at the ends of the stem and branches. Involucre obovoid, or campanulate, its bracts appressed, imbricated in few series, the outer shorter. Receptacle nearly flat or convex, chaffy, the membranous chaff subtending the disk-flowers. Ray-flowers pistillate, fertile, the rays white or pink. Disk-flowers perfect, fertile, their corollas yellow, 5-lobed. Anthers obtuse and entire at the base. Style-branches of the disk-flowers truncate. Achenes oblong or obovate, slightly compressed. Pappus none. [Named for Achilles.]
About 75 species, natives of the northern hemisphere, mostly of the Old World. Besides the following, another, or perhaps 2 others, occur in northwestern North America. Type species: Achillea santolina L.
Involucre broadly campanulate; leaves serrate.
1. A. Ptarmica.
Involucre ovoid to cylindric; leaves finely dissected. Involucral bracts greenish-yellow; rays small.
Plant loosely woolly or nearly glabrous; inflorescence flat-topped.
2. A. Millefolium.
Plant densely woolly; inflorescence convex.
3. A. lanulosa.
Involucral bracts black-margined; rays large.
4. A. boreal is.
Achillea Ptarmica L. Sp. Pl. 898. 1753.
Perennial from horizontal or creeping rootstocks; stem glabrous, or slightly pubescent, nearly or quite simple, 1°-2° high. Leaves linear or linear-lanceolate, sessile and slightly clasping at the base, acute at the apex, regularly and closely serrate, sometimes pubescent on the veins beneath, 1'-2 1/2' long, 1 1/2"-3" wide; heads not very numerous, 5"-9" broad; peduncles puberulent; involucre broadly campanulate, its bracts ovate-oblong, obtuse or obtusish, slightly tomentose; rays 5-15, white, rather large.
In moist soil, Newfoundland, New Brunswick and Quebec to Massachusetts and Michigan. Naturalized from Europe. Native also of northern Asia. Goose-tongue. Wild, bastard-or european pellitory. Fair-maid-of-France. Sneezewort-tansy. July-Sept.
Achillea Millefolium L. Sp. Pl. 899. 1753.
Perennial from horizontal rootstocks; flowering stems pubescent, or nearly glabrous, simple, or corymbosely branched above, 1°-2° high. Basal leaves, and those of the numerous short sterile shoots, mostly petioled, sometimes 10' long and 1/2 wide, those of the stem sessile, all narrowly oblong or lanceolate in outline and finely dissected into narrow pinnatifid segments, tomentose, pubescent or nearly glabrous; heads numerous, 2"-3" broad, in terminal compound dense, somewhat convex or nearly flat-topped corymbs; involucre ovoid-cylindric, its bracts oblong, obtusish, pubescent; rays 4-6, white, or often pink or- purple, less than 2" broad.
In various situations throughout eastern North America, often occurring as a naturalized weed. Native also of Europe and Asia. Old names, sanguinary, thousand-leaf, nosebleed, old-man's-pep-per, soldier's-woundwort, gordaldo. June-Nov.