COMPOSITE. (COMPOSITE FAMILY.) 203 



leaves pinnately 5 to 7-parted into very narrow linear and by revolution fili- 

 form entire divisions : involucre minutely cinereous-canescent, becoming 

 glabrate. — Proc. Am. Acad. xix. 48. Plains of Southern Colorado and New 

 Mexico. 



+♦+♦+♦ Heads small and narrow, very few-flowered : flowers glabrous: stems 



woody at base. 



19. A. Bigelovii, Gray. Silvery-canescent throughout, a foot high: 

 leaves from oblong- to linear-cuneate, mostly 3-toothod at the truncate apex, 

 about \ inch long : heads very numerous and crowded in the oblong or virgate 

 thyrsiform panicle, tomentose-canescent, containing only one or two hermaph- 

 rodite and as many female flowers, all fertile. — Pacif. R. Rep. iv. 110. Rocky 

 banks, Colorado, on the Upper Canadian and Arkansas. 



§ 3. Heads homogamous, the flowers all hermaphrodite and fertile: receptacle not 

 hairy. — Seriphidium. Ours are the true "Sage-brushes," being rather 

 shrubby, canescent or silvery with a fine or close tomentum, and heads not 

 nodding. 



20. A. arbuscula, Nutt. Dwarf, a span or rarely a foot high, with u, 

 stout base and slender flowering branches : leaves short, cuneate or flabelliform, 

 3-lobed or parted, with the lobes obovate to spatulate-linear, sometimes again 2-lobed ; 

 those subtending the heads usually entire and narrow : panicle strict and com- 

 paratively simple and naked, often spiciform and reduced to few rather scat- 

 tered sessile heads : involucre 5 to 9-flowered. — High mountains and elevated 

 plains, from Wyoming and Utah to Idaho and California. 



21. A. tridentata, Nutt. Larger, 1 to 6 (or even 12) feet high, ranch 

 branched : leaves cuneate, obtusely 3-toothed or 3-lobed, or even 4 to 7-toothed, at the 

 truncate summit, uppermost cuneate-linear : heads densely paniculate : involucre 

 5 to 8-flowered, its outer or accessory tomentose-canescent bracts short and 

 ovate. — Prom Montana to Colorado and westward. Immensely abundant ; the 

 characteristic " Sage-brush," or " Sage-wood." 



22. A. trifida, Nutt. A foot or two high, sometimes lower, much 

 branched : leaves 3-clefl and 3-parted ; the lobes and the entire upper leaves nar- 

 rowly linear or slightly spatulate-dilated : heads numerous in the contracted 

 leafy panicle, or spicately disposed on its branches : involucre 3 to ^-flowered, 

 rarely 6 to 9-flowered, its outer or accessory bracts oblong to short-linear or 

 lanceolate. — Wyoming and Utah to Washington and California. 



23. A. cana, Pursh. A foot or two high, freely branched, silvery canes- 

 cent : leaves lanceolate-linear or narrower, somewhat tapering to both ends, an 

 inch or two long, entire, rarely with 2 or 3 acute teeth or lobes, margins not re- 

 volute : heads glomerate in a leafy contracted panicle, 6 to 9-flowered, rarely 

 5-flowered, usually with one or two linear subulate accessory bracts. — Plains, 

 Saskatchewan to Montana, the Dakotas, and Colorado. 



66. PETASITBS, Tourn. Bdtter-bur. Sweet Coltsfoot. 



Perennial herbs, with thickish and creeping rootstocks, sending up scapiform 

 simple flowering stems and ample radical leaves on strong petioles, cottony- 

 tomentose or glabrate ; the flowers whitish or purplish. 



