OOMPOSIT^E. (COMPOSITE FAMILY.) 203 



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

 form entire divisions : involucre minutely cinereous-faiiescent, l>ecoiniij|^ 

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

 Mexica 



4H. *+ 4^ Heads small and narrow^ very few-fiowered : Jloners ylabrous: stents 



woodtj at base. 



19. A. Bigelovii, Gray. Silvery-canescent tlirou^Hiout, a foot hi^'h : 

 leaves from oblong- to linear-cuneate, mostly ;3-tootli?d at the truncate apex, 

 about ^ inch long : heads very numerous and crowded in the oi)loiig or virgate 

 thyrsiform panicle, tomentose-canescent, containin'^ only one or two lierniaph- 

 rodite and as many female flowers, all fertile. — Pacif. H. liep. iv. 1 10. Kucky 

 banks, Colorado, on the Upper Canadian and Arkansas. 



§ 3. Heads homoqamous, the flowers all hermaphrodite and fertile: recejitacle not 

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

 shrubbj/, canescent or silvery with a flne or close toinentum, and heads not 

 nodding. 



20. A. arbuSCUla, 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 ohovaie to spatulate-linear, sometimes again 2-lob(d ; 

 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 mouutaius and elevated 

 plains, from AVyoming and Utah to Idaho and California. 



21. A. tridentata, Nutt. Larger, I to 6 {or even 12) feet high,nn\ch 

 branched : leav(-s nnieate, 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, Xutt. A foot or two high, sometimes lower, much 

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

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

 leafy panicle, or spicately disposed on its branches : involucre 3 to r^floirrred, 

 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. Caua, 1 ursli. A foot or two high, freely branched, s//rer^ canes- 

 cent : leaves lanceolate-linear or narrower, somewhat tapenny to both tuds, an 

 inch or two long, entire, rarely with 2 Or 3 acute teeth or lubes, margins not ro- 

 volute : heads glomerate in a leafy contracted panicle, G to [)-flouered, rart-ly 

 5-flowered, usually with one or two linear subulate accessory bracts. — I'laius, 

 Saskatchewan to Montana, the Dakotas, and Colorado. 



66. PETASITES, Tourn. Butter-bdr. Sweet Coi.tsfoot. 



Perennial herbs, with tliickisli and creeping rooftocks. sen«]ini: up scapiform 

 simple flowering stems and lanple radical leaves on strong petioleh, cottony- 

 tomentose or glabrate ; the flowers whitish or purplish. 



