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..
Artemisia tridentata Nutt. Trans. Am. Phil. Soc. (II) 7: 398. 1841.
Shrubby, silvery-canescent; stem much branched, 1°-12° high. Leaves narrowly cuneate, 1/2'-1 1/2' 1/2 long, 1"-3" wide, sessile, 3-7-toothed at the truncate apex; heads very numerous, 5-8-flow-ered, about 1 1/2" broad, sessile, or very nearly so, in large dense panicles; involucre oblong, tomentose, its inner bracts oblong, the outer short, ovate, all obtuse or obtusish; receptacle naked; flowers all perfect and fertile.
On dry plains and in rocky soil, western Nebraska to Colorado, Utah and California, north to Montana and British Columbia. July-Sept.
Artemisia cana Pursh, Fl. Am. Sept. 521. 1814.
Shrubby, densely white-canescent; stem much branched, 1°-2 1/2° high. Leaves linear, linear-oblong or narrowly lanceolate, sessile, acute at both ends, 1'-2' long, 1 1/2"-3" wide, usually quite entire, rarely with 2 or 3 acute teeth or lobes; heads numerous, about 1 1/2" broad, glomerate or sometimes solitary in the axils of the leaves, or crowded into a naked thyrsus at the summit, 5-9-flowered; involucre oblong, canescent, its inner bracts oblong or lanceolate, obtuse, usually with 1-3 shorter outer ones; receptacle naked; flowers all perfect and fertile.
Plains, Nebraska and Colorado to North Dakota, Montana and Saskatchewan. July-Sept.