254 COMPOSITAE. 



pistillate flowers slender and small, 2- or 3-toothed, those of the 

 perfect flowers enlarged above, 5-toothed; akenes obovoid or 

 oblong, almost always glabrous. 



Green and glabrous. 



Perennial; leaves linear, mostly entire. A. dracunculoides. 



Biennial; leaves 1-2-pinnateIy parted. A. biennis. 



Canescent or tomentose. 



Leaves narrowly 3-5-parted into linear segments. A. rig 



Leaves and segments broader. 



Receptacle pilose; involucre canescent. / 



Receptacle not pilose; involucre not canescent. 



Involucre white-tomentose; herbage not glan- 

 dular. A. gnapkalodes. 

 Involucre glabrous or nearly so; herbage atom- 

 iferous glandular. A. atomifera. 



Artemisia dracunculoides Pursh. Perennial, herbaceous, very odorous, 

 usually tufted, the slender stems 100-150 cm. high, glabrous throughout; 

 leaves linear, entire or 3-cIeft, 2-10 cm. long, numerous; heads nodding, 

 numerous, in large and leafy panicles; involucre campanulate, glabrous, 2 mm. 

 high; disk-flowers sterile; receptacle naked; akenes glabrous. Common in 

 the valleys. 



Artemisia biennis Willd. Biennial, glabrous, the stems simple, 30-50 

 cm. high, leafy to the top; leaves numerous, 5-8 cm. long, all 1— 2-pinnately 

 parted into linear acute entire or toothed segments; heads small, in short 

 spikes in the axils of the uppermost leaves crowded in a slender leafy panicle; 

 involucre campanulate, 3 mm. broad, the bracts green scarious-margined; akenes 

 oblong; pappus none, receptacle naked. Colton, Piper: Waitsburg, Horner. 



Artemisia rigida (Nutt.) Gray. Scabland Sagebrush. Perennial, woody 

 at base, the branches erect, strict, 15-30 cm. high, leafy to the top; leaves 

 rigid, silvery-canescent, mostly cleft or parted into 3-5 linear segments, rarely 

 simple, 1-3 cm. long; inflorescence a leafy spike, the heads solitary in the axils; 

 involucre oblong-campanulate, 3 mm. long, S-12-flowered; flowers all alike, 

 perfect. In thin rocky soil. 



Artemisia absinthium L. Wormwood. Half shrubby, much branched, 

 50-100 cm. high, silvery-canescent throughout; leaves 2-3 times pinnately 

 parted, the segments lanceolate, acute; heads hemispheric, 3-5 cm. broad, 

 in rather dense panicles; bracts mostly oblong, obtuse, scarious-margined. 

 Introduced and spreading. 



Artemisia gnaphalodes Nutt. Perennial, herbaceous, 30-90 cm. high, 

 densely white-tomentose throughout; leaves 2-6 cm. long, lanceolate and entire 

 or 3-5-toothed or cleft into linear or lanceolate lobes, persistently tomentose 

 beneath, often glabrate above; heads in large usually dense panicles; involucre 

 oblong-campanulate, 3-4 mm. long, persistently white- woolly; receptacle 

 naked; disk-flowers fertile. Common and variable. 



Artemisia atomifera Piper. Much like A. gnaphalodes, the leaves usually 

 more deeply lobed, early becoming glabrous above; involucre becoming gla- 

 brous or nearly so, at least when mature; herbage minutely atomiferous glan- 

 dular throughout. Common on the banks of Snake River. 



380. ANTENNARIA. Everlasting. 



Low white-woolly cespitose perennials; leaves alternate, entire; 

 heads small, solitary or corymbose, completely dioecious; re- 



