COM POSIT A L 



bristles also); that of disk Ms. of both 

 squamellae and bristles 



8 . Erigeron 

 (E. annuus) 



Phyllaries distinctly unequal and graduat- 

 ed, of firm texture, often with short 



herbaceous tip: pappus otherwise 7. Aster 



SS. Pappus not of numerous slender hairs, sometimes wanting. 

 V. Lvs. all or mostly opposite. 



W. Rays sessile, indurated and persistent on the achenes: lvs. 

 entire: involucre strongly graduated and regularly im- 

 bricated 16 - Zinnia 



WW. Rays contracted into a short but slender tube, not indurated 

 and persistent in fr. : lvs. not entire (except in Eclipta): 

 involucre not strongly graduated nor regularly imbricat- 

 ed. 

 X. Rays numerous, small, very narrow, white, about 2-seriate; the 

 whole head little if at all over 1cm. wide: pappus none: 



lvs. entire or merely toothed 19. Eclipta 



XX. Rays otherwise: pappus often present: lvs. usually pinnately 

 divided or finely pinnatifid. 

 Achenes beaked: lvs. twice pinnatifid into nearly filiform 



segments 26. Cosmos 



Achenes not beaked, although sometimes slender: lvs. not 

 divided into filiform segments. 

 Pappus of 2-4 retrorsely hispid stiff awns: heads only 2 cm. 



wide or less across the rays 25 . Bidevs 



Pappus of 2 small teeth, or none: heads about 5 cm. wide 



or more across the rays 24 . Dahlia 



VV. Lvs. all alternate or (in one case) strictly basal. 



Y. Lvs. finely dissected into segments less than 1 mm. 

 wide : heads small, densely crowded into terminal 



corymbs; receptacle chaffy 29. Achillea 



YY. Lvs. not finely dissected: heads otherwise; receptacle 

 naked. 

 Z. Heads tiny, 4-6-fld.: lvs. few, linear or narrowly 

 lanceolate, 5-30 mm. long: fr. oblong, nar- 

 rowly 3-winged, more than twice as long 



as involucre, epappose 14 . Sheareria 



ZZ. Heads medium-sized or large, many-fid.: lvs. 

 otherwise: fr. otherwise. 



Plant scapose, the scapes 1-headed 5. Bellis 



Plants not scapose. 



Involucral bracts not with scarious margin 



and tip : style brs. acute 7 . Aster 



Involucral bracts with scarious margin and 



tip : style brs. truncate 30. Chrysanthemum 



RR. Rays yellow or orange, sometimes with a red, brown or purplish 

 spot or blotch in lower part, rarely (Gaillardia) only 

 the tip yellow. 

 A'. Pappus of fine hair-like bristles only. 



391 



