COMPOSITE. (COMPOSITE FAMILY.) 208 



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. 



w. -w. *-. 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-toothed 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. arbllSCllla, Nutt. Dwarf, a span or rarely a foot high, with a 

 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, I to & (or even 12) feet high, much 

 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. From 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-cleft 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 5-flowered, 

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

 lanceolate. Wyoming and Utah to Washington Territory 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 revolute : 

 heads glomerate in a leafy contracted panicle, 6 to S-flowered, rarely 5-flowered, 

 usually with one or two linear subulate accessory bracts. Plains, Saskatche- 

 wan to Montana, Dakota, and Colorado. 



66. PETASITES, Tourn. BUTTER-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. 



