800 



COMPOSIT A E (COM POSIT K F A M IL V ) 



like tips. Receptacle flat, alveolate. Achenes more or less flattened ; pappus 

 simple, of capillary bristles (double in 4 and 6). Perennial herbs (annual 

 only in 7 and 8), with corymbed, panicled, or racemose heads, flowering 

 chiefly in autumn. Rays white, purple, blue, or pink ; the disk yellow, often 

 changing to purple. Species often without sharply defined limits, freely hybrid- 

 izing. (Name d<rrrip, a star, from the radiate heads of flowers.) 



N.B. In this genus the heads are drawn on a scale of f, the leaves |. 



A. At least the basal leaves cgrdate and definitely petioled B. 

 B. Stem-leaves petioled or sessile, not clasping C. 

 C. Rays white D. 

 D. Plant not glandular E. 

 E. Heads corymbose. 



Involucre ovoid-campanulate, thick -cylindric, or turbinate ; 



tufted basal leaves few or none. 

 Leaves thin, smoothish, at least not rough above 

 Leaves thick, rough above. 



Inflorescence slightly forking ; heads few, 1-1.5 cm. high 

 Inflorescence much branched ; heads numerous, hardly 



1 cm. high 



Involucre slender, cylindric ; large tufted basal leaves abun- 

 dant . 



E. Heads paniculate 



D. Glandular, at least as to the branches of the inflorescence . 

 C. Rays blue or violet F. 

 F. Plant not glandular G. 



G- Involucral bracts with squrroase tips ; rays many (about 40) . 



G. Involucral bracts appressed or ascending; rays fewer (10-20) //. 



//. Leaves entire or essentially so, firm, much longer than wide. 



Leaves harsh above 



Leaves smooth above 



H. Leaves serrate, mostly thinner I. 



I. Involucre 4-6 mm. high ; bracts appressed, with conspicu- 

 ous colored tips ; heads abundant, paniculate. 

 Cordate leaves mostly on slender petioles, neither glau- 

 cous nor very smooth 



Cordate leaves mostly on winged petioles, glaucous be- 

 neath, smooth 



I. Involucre 6-10 min. high ; bracts loose, without conspicu- 

 ously colored tips. 

 Heads abundant, densely racemo-paniculate. 



Stem essentially glabrous 



Stem densely short-pubescent 



Heads fewer, loosely paniculate or subcorymbose . 

 F. At least the branches of the inflorescence glandular 



B. Stem-leaves mostly cordate-clasping 



A . None of the leaves at once cordate and definitely petioled J. 



./. At least the lower leaves abruptly narrowed or constricted below 



the middle. 

 Leaves essentially entire, at most slightly constricted above the 



2. A. divaricatnu. 



3. A.furcatuK. 



4. A. 



5. A. Si- 

 28. A. 



6. A. macrophyllux. 



19. A. anomahis. 



20. A. aznreuH. 

 21. A. Shortii. 



23. A. cordifoliu*. 



24. A. Lowrieiinu*. 



25. A. sag Mi foli it*. 



26. A. Drummondii. 



27. A. Li inlli yitnitx. 

 6. A. maorophyltut. 



22. A. 



base 



Leaves sharply serrate, the lower contracted to winged petioles. 

 Leaves with abruptly dilated auriculate-clasping " 

 Leaves without dilated bases, scarcely clasping 

 J. Leaves not abruptly narrowed or constricted below A". 

 A'. Stem lc;ivos with cordate- or auriculate-clasping bases L. 

 /.. Involucre glandular-hairy ; rays usually deep violet M. 

 .)/. Leaves conspicuously cordate-clasping, mostly entire. 



Branchlets glandular-viscid ; involucre hemispherical; bracts 



subequal, linear-attenuate, loose 



Branchlets not glandular ; involucre turbinate; bracts un- 

 equal, linear-oblong, with slightly spreading green tips . 

 M. Leaves obscurely cordate-clasping. 



Plant rigid, freely branching ; leaves mucronate-tipped ; in- 

 volucral bracts unequal, linear or linear-oblong, with 



spreading tips 



Plant not rigid, bearing few terminal heads; leaves thin, 



acuminate ; bracts equal, linear-attenuate 

 L. Involucre not glandular-hairy .V. 

 N. Bracts of the involucre distinctly Imbricated, i.e. the outer 



series successively shorter O. 

 (>. Plant smooth and glaucous. 



Leaves lanceolate to ovate ; heads paniculate 

 Leaves narrower ; heads solitary or racemose . 

 O. Plant not glaucous. 



Tips of bracts squarrose or recurved-spreading. 



18. A. patens. 



48. A.prenanthoides. 

 47. A. tardiflorus. 



14. A.novae-anylitH'. 

 18. A. 



13. A. oWongifoliu*. 

 15. .1. modestus. 



29. A. ?aeri*. 

 80. A. virytitux. 



