WILU FLOWKKS OK \K\V VOKK 3OI 



Involucre ovoid, canii)anulate or turbinate; its bracts mostly obtuse 

 or rounded; basal leaves few and small, or commonly none 

 (except A. g 1 o m e r a t u s) 

 Leaves membranous or thin, smooth or nearly so 



Heads short-peduncled, three-fotirths of an inch broad or less, 



the disk turning crimson; leaves acute or short-acuminate 



2 A. c a r m e s i n u s 



Heads long-peduncled, three-fotirths of an inch broad or more, 



the disk turning brown or reddish; leaves long-acuminate 



Heads i inch broad or more; leaves of the branches large, 



long, lanceolate, acuminate 3A. tenebrosus 



Heads three-fourths to i inch broad ; leaves of the branches 



small, obtuse or acute 4 A. d i \- a r i c a t u s 



Leaves thick, firm, rough; heads one-third to one-Iialf of an inch 

 high; inflorescence paniculate or glomerate 

 Leaves acute or short-acuminate, pilose beneath; inflorescence 



glomerate 5 A. g 1 o m e r a t u s 



Leaves long-acuminate ; not pilose beneath ; inflorescence open- 

 paniculate 6 A . c 1 a >• t o n i 



Involucre cylindric; its bracts tapering to an obtuse apex; basal leaves 

 large, tufted 

 Bracts of the involucre pale, scarious, usually without herbaceous 



tips 7 A. c u r V c s c e n s 



Bracts of the in\'olucre broader, with herbaceous tips 



S A. s c h r e b e r i 

 Rays violet, usually three-toothed; plants glandular 



Predominant glands large, capitate; leaves thick, coarse, heavy 



Sinus broad; glands chiefly confined to the inflorescence; plant 



usually harsh g A. m a c r o p h y 1 1 u s 



Sinus narrow; glands abundant on the lea\-es and stem; growing 



plant clammy 10 A. r o s c i d u s 



Predominant glands minute, scarcely capitate; leaves usually thin 



Inflorescence very irregular, paniculate-corymbose; plants often 4 to 

 5 feet high; broader leaves large, cordate, acute. .11 A. n o b i 1 i s 

 Inflorescence rather regular, flat, or convex-topped; plants usually 

 less than 25 feet tall 



