ig6 Flora of the Palousc Region 



hyaline chaffy scales with a prominent midrib which is prolonged 

 into a naked awn, or in the sterile rays scales awnless: akenes ob- 

 long, top-shaped, each surrounded by a tuft of hairs. 



G. aristata Pursh. Perennial, erect, 30-60 cm. high, rough-pubescent: 

 lower leaves spatulate, long-petioled, the upper sessile, all entire or more or 

 less pinnately-lobed, 5-12 cm. long: heads long-peduncled: involucre hairy, 

 the lanceolate acuminate bracts unequal, the longest about 1 cm.: disk flow- 

 ers dark-purple: rays 10-18, yellow, purplish at base, 1.5-2 cm. long: bristles 

 of the receptacle as long as the akenes or longer. Low ground, common. 



329. ACHILLEA. 



Perennial herbs, rather strong-scented: leaves alternate, serrate 

 or pinnately dissected: heads small, in corymbs, many-flowered: 

 flowers yellow, white or sometimes rose-colored, all fertile; ray- 

 flowers few or several, mostly short or broad, pistillate: involucre 

 narrow, the scales imbricated in a few rows, appressed: receptacle 

 flattish to conical, with thin chaff: pappus none: akenes oblong or 

 ovate, obcompressed, surrounded by a narrow and cartilaginous 

 margin. 



A. millefolium var. lanulosa Piper. (A. lanulosa Nutt.) Perennial, 

 erect, usually tufted, 30-60 cm. high, loosely pubescent throughout with 

 white somewhat woolly hairs: basal-leaves short-petioled, oblong or oblong- 

 lanceolate, 8-20 cm. long, pinnately divided into very numerous segments; 

 segments once or twice pinnately-cleft or parted into linear acute lobes: 

 heads small, numerous, in convex or flat-topped terminal corymbs; involucre 

 ovoid or subglobose, 3-5 mm. high: rays 4-5, white, 2-4 mm. long. Abund- 

 ant everywhere, 



330. ANTHEMIS. 



Herbs: leaves alternate, mostly tripinnately divided: heads 

 many-flowered: ray r -flowers numerous, commonly conspicuous, 

 pistillate or sometimes sterile; disk-flowers fertile: involucre broad, 

 the scales very numerous, imbricated and appressed: receptacle 

 convex to oblong-conical, chaffy, with slender or thin scales or 

 awns, subtending at least the central flowers: pappus none, or a 

 short chaffy crown: akenes obovoid or oblong, 4-5-angled, 8-10- 

 ribbed or many-striate, truncate at the apex. 



A. COtllla Iy- Annual, much branched, puberulentor glabrate, 30-60 cm. 

 high: leaves 1-3 times piunately-dissected into thread-like lobes: heads 2 cm. 

 broad: receptacle conical, with bristly bractsnear the apex, none at the base: 

 invo'iucral bracts oblong, obtuse, pubescent; rays white, 10-18, becoming re- 

 flexed in age: akenes 10-ribbed, roughened: pappus none. A weed, becom- 

 ing common, the herbage strong-scented. 



331. CHRYSANTHEMUM. 



Herbs: heads many-flowered: flowers all with corollas; ray- 

 flowers usually elongated, numerous, pistillate; disk-flowers usu- 



