902 COMPOSITAE 



Leaves not thin or lobed; achenes somewhat quadrangular- 

 obovoid, 3-4-sided, truncate at the summit. 



Ray flowers pistillate, fertile, the rays persisting 



9157. Heliopsis, p. 963. 



Ray flowers neutral, sterile, the rays deciduous 



9200. Helianthus, p. 970. 



D. Leaves alternate. 



E. Pappus of terete awns or bristles. 

 Pappus of terete awns. 



Involucres very glutinous; bracts glabrous and hooked; awns 



smooth and deciduous; receptacle not chaffy 



8833. Grindelia, p. 913. 



Involucres not glutinous; bracts not hooked, not deciduous; 



receptacle chaffy 9237. Bidens, p. 981. 



Pappus of capillary bristles. 



Involucres with conspicuous, oblong glands; leaves dissected. 



9312. Dyssodia, p. 988. 



Involucres lacking conspicuous glands. 



Rays many, 40-200, arranged in more than 1 row 



8901. Erigeron, p. 947. 



Rays fewer than 40, arranged in one row. 

 Bracts of involucre in 1 series, sometimes with a few bract- 

 lets at the base of the involucre; rays yellow 



9411. Senecio, p. 996. 



Bracts of the involucre in more than 1 series. 

 Rays yellow. 



Involucres 2.5-10 cm in diameter . .9061. Inula, p. 955. 

 Involucres 0.5-2.3 mm in diameter. 



Pappus double, the outer row of very small, chaffy 

 bristles, much shorter than the inner row of 



numerous capillary bristles 



8844. Chrysopsis, p. 914. 



Pappus simple, of numerous slender and equal bristles. 



8849. Solidago, p. 914. 



Rays violet, purple, blue, or white. 



Bracts few, 3-6, firm and thick, the inner ones blunt or 

 rounded and green at the apex, the green part 

 more or less inconspicuously glandular-punctate; 



heads corymbose; flowers white 



8904. Sericocarpus, p. 949. 



Bracts not as above; flowers mostly colored 



8900. Aster, p. 928. 



E. Pappus none or a cup or crown, or of thin chaffy scales. 



Plants with the stem leaves decurrent; pappus of 5-8 thin, 1-nerved 

 chaffy scales, the nerve usually ending in a bristle or point. 



9305. Helenium, p. 987. 



Plants not as above. 

 Receptacle naked. 



Rays yellow 9227. Coreopsis, p. 979. 



Rays white. 



Leaves entire or mostly so; involucres less than 8 mm wide. 



8892. Boltonia, p. 928. 



Leaves coarsely dentate to pinnatifid; involucres more than 



8 mm wide 9341. Chrysanthemum, p. 990. 



Receptacle chaffy, at least at the summit. 



Rays sterile, neutral or rarely pistillate; disk flowers perfect 

 and fertile. 



