396 Karl M. Wiegand and Arthur J. Eames 



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d. Pappus of scales, which are sometimes deciduous (see also 3d d and 

 4th d). 

 c. Receptacle chaffy. 



/. Rays white ; heads very small 20. Galinsoga 419 



/. Rays yellow ; heads large 18. Helianthus 415 



c. Receptacle not chaffy ; rays yellow 21. Helen ium 420 



d. Pappus none or a mere crown (see also 4th d). 

 e. Receptacle not chaffy ; rays white or pinkish. 



/. Rays more than 30 ; low scapose plants 5. Bellis 402 



/. Rays less than 30 ; leafy plants 24. Chrysanthemum 421 



e. Receptacle chaffy. 

 /. Rays white. 



g. Heads small, 3-7 mm. in diam. ; achenes flattened. .22. Achillea 420 

 g. Heads large, 13-30 mm. in diam.; achenes terete.. 23. Anthemis 420 

 /. Rays yellow. 



g. Rays neutral 17. Rudbeckia 414 



g. Rays pistillate. 



h. Disk flowers perfect, but sterile; leaves large, thin, and lobed; 



plant hairy 13. Polymnia 413 



h. Disk flowers perfect and fertile; leaves smaller; plant pubes- 

 cent or glabrous. 



i. Leaves dissected 23. Anthemis 420 



i. Leaves undivided, ovate 16. Heliopsis 414 



d. Pappus capillary ; receptacle not chaffy. 

 e. Rays yellow, or rarely cream color. 

 /. Involucral bracts in one series, often with minute bractlets at base. 

 g. Heads solitary, on scapose scaly-bracted stems, appearing before 



the leaves 27. Tussilago 422 



g. Heads several, on leaf-bearing stems 30. Senecio 423 



/. Involucral bracts in 3-many series. 



g. Heads large, 2.5-10 cm. in diam 12. Inula 412 



g. Heads small, 0.5-1.5 cm. in diam 4. Solidago 398 



e. Rays violet, purple, blue, or white. 

 /. Involucral bracts in 1-2 series. 



g. Leaves large, reniform, basal 28. Petasites 423 



g. Leaves smaller, obovate or narrower, cauline and basal. 



7. Erigeron 407 

 /. Involucral bracts in 3-5 series. 

 g. Bracts firm; rays few (3-6), white; leaves spatulate or obovate; 



heads corymbose 8. Sericocarpus 408 



g. Bracts membranous or herbaceous ; rays mostly more numer- 

 ous, white, purple, or blue ; leaves various ; heads corymbose or 



paniculate 6. Aster 403 



a. Flowers of the head all ligulate ; juice usually milky. 



b. Pappus none 37. Lapsana 427 



b. Pappus of scales 38. Cichorium 427 



b. Pappus of bristles or hairs. 

 c. Bristles plumose (seen best when mature and dry). 



d. Receptacle chaffy ; leaves not grass-like 39. Hypochaeris 427 



d. Receptacle not chaffy, sometimes setose. 



e. Leaves linear, grass-like, cauline 42. Tragopogon 427 



e. Leaves not grass-like. 



/. Plant scapose ; inner achenes beaked 40. Apargia 427 



/. Plant leafy-stemmed; achenes all alike, not beaked 41. Picris 427 



