576 



COMPOSITAE (composite FAMILY) 



clusters, on very short peduncles; scales of the involucre 4-5. — Wyoming to 

 Idaho and Utah. 



4. TetradymiaspinosaH. & A. Bot, Beech. 360. 1840. A rigidly branched 

 shrub 6^12 dm. high; stems densely white-tomentose: primary leaves modi- 

 fied into rigid spines which may be either straight or reciu-ved, 1-A cm. long, 

 tomentose or glabrate; secondary fascicled leaves commonly present, small, 

 Hnear-clavate, glabrous or early glabrate: heads on stout peduncles arising 

 from the leaf-axils; involucre about 8 mm. high, usually 6 or 7-fiowered; 

 bracts 5 or 6, the outer ones oblong, thfe inner ones broadly oblong to nearly 

 orbicular, all obtuse: achenes with soft white wool nearly equaling the rigid 

 pappus-bristles. — ^Desert areas; from Wyoming and Colorado to Cahfomia and 

 Oregon. 



90. SENECIO L. 



Herbs or woody, plants with alternate leaves and with heads in terminal 

 cjones or rarely solitary. Heads ihany-fiowered, radiate or discoid; flowers 

 in our species yellow. Involucre cyhndrical to campanulate, of several or 

 numerous connivent-erect herbaceous, equal bracts, mostly with 1 or 2 rows 

 of outer erect bracteoles at base, which are elongated and exceed the proper 

 involucre in a few; species. Receptacle flat, naked. AjQthers mofetly rounded 

 at base. Style-branches truncate. Achenes terete. Pappus of abundant 

 white aiid soft bristles. 



Heads large, 15-25 mm. high, usually more or less nodding. 

 Rayless. 



Heads 15-20 mm. long 



Heads 8-12 mm. long , * 



Rays present. 



Stem leaves clasping 



Stem leaves usually short-petioled, not clasping. 

 Leaves tapering gradually to the petiole. 



Plant glabrous ........ 



Plant aracbnoid-tomentose 



Leaves tapering abruptly into the petiole , . 

 Heads smaller, less than 15 mm., high, not noticeably nodding. 

 Biennials or perennials. 



Leaves not at all pinnate or pinnatifid. 



Stems often numerously ^.nd always nearly equably leafy to 

 the top. 

 Leaves not linear. 



Leaves obovate to elliptic, entire to repand-dentate, 

 obtuse. 



Peduncles verj^ short 



Peduncles distinctly surpassing the leaves 

 Leaves triangular to lance-linear, acute. 

 ' - Some or all of the leaves triangular or Ibnce-cordate , 

 None of the leaves triangular or lance-cordate. 

 Stem3 5-12dm. high; leaves sessile, serrate . 

 Stems 4 dm. or less high; leaves petioled. 

 Rays present . > . . . 

 Rays wanting , . , . ,- 



Leaves linear 



Stems either few-leaved or with the upper leaves reduced in 

 size. I ■ ; 



, I , Tall C7-15dm.):bog-plant with glaucous, fleshy leaves ,, 

 Lower, 6 dm. or less nigh. 

 Sterna niori^ or less leafy. 



Leaves glabrous or glaucous (at least in age). 

 - Leaves sharply dentate. 



Rays wanting . 



" ' Rays present 



Leaves entire or callous-denticulate. 

 Le^,ves not glaucous , , . . , 

 Leaves glaucous or glauc'escent. 



Involucral bracts black-tipped , , 

 Involucral bracts not blacK-tipped 

 Leaves and stems at first woolly-pubescent or floccpse, 

 but often early glabrate. 

 Loosely woolly-pubescent, becoming glabrate. 

 Leaves entire; involucral bracts not black- 

 , tipped ........ 



Leaves dentate or denticulate; involucral bract 

 ' blabk-tippftd. 



1. S. Bigelovii. 



2. S. cemuus. 



3. S. amplectens. 



4. S. Holmii. 



5. S. taraxacoides. 



6. S. Soldanella. 



7. S. carthamoid^. 



8. S. Fremontii. 



9. S. triangularis. 



10. S. serra. 



11. S; orassulus. > ' 



12. S. rapifolius. 

 40. S. spartioides. 



13. S. hydrophilus. 



12. S. rapifolius. 



11. S. crassulus. 



16. S. integeriimus. 



14. S. glaucescens. 



15. S. anacletus. 



16. -S, integerrimus; 



