Artemisia tridentata (Nutt.) W. A. Weber

Artemisia tridentata Nutt. Trans. Am. Phil. Soc. II. 7: 398 1841.
A shrub, 5-50 dm. high, much branched, with straw-colored bark; leaves canescent, 1-4 cm. long, narrowly cuneate, obtusely 3-toothed (rarely 4-7-toothed) at the apex, or the uppermost entire, linear or oblanceolate; heads numerous, sessile, clustered in dense leafy panicles; involucre campanulate, 3-4 mm. high, about 2 mm. broad; bracts about 15, in 4-5 series, imbricate, canescent, the outermost short, thick, ovate, acute, less than a foiu-th as long as the innermost; inner bracts oblong, obtuse, thinner with scarious margins; flowers 4-8; corollas trumpet-shaped, 5-toothed, 2.5-3 mm. long; tube densely glandular-granuliferous, equaling the almost glabrous throat; style equaling the corolla; achenes about 1.5 mm. long.
Type locality: Plains of the Oregon [Columbia Rivcrl.
Distribution: South Dakota and Montana to British Columbia, I.ower California, and New Mexico.