COMPOSITES 433 



ee. Foliage leaves entire, toothed, or broad- 

 lobed. 

 F. Achenes curved or horse-shoe-shaped.. . . 14. Calendula 

 ff. Achenes straight. 



g. Torus flat or slightly convex 15. Chrysanthemum 



GG. Torus conical. 



h. Rays yellow: Sowers large, 2-3 in.. .16. Rudbeckia 

 nu. Rays not yellow: flowers about 



1 in. across: plant low 17. Bellis 



cc. Pappus of 2 thin early deciduous scales 18. Helianthus 



ccc. Pappus a short crown, or achenes awned at the 

 top with (2 or more) awns. 

 d. Achenes angled or ribbed, crowned with cup- 

 like or lobed pappus: foliage strongly 



"tansy" scented 19. Tanacetum 



dd. Achenes more or less flattened, and awned 

 at summit, with usually 2 or 4 awns. 

 e. Awns barbed downward: achenes various, 

 narrowed at top, and awned, but not 



really beaked 20. Bidens 



ee. Teeth not downwardly barbed: (some- 

 times achenes awnless. ) 21. Coreopsis 



cccc. Pappus of many bristles. 



d. Plant very prickly 22. Cirsium 



dd. Plant not prickly. 



e. Involucre prickly and bur-like 23. Arctium. 



ee. Involucre not bur-like or prickly. 



F. Torus bristly (chaff or bracts amongst 



the florets) 24. Centaurea 



ff. Torus naked. 

 g. Rays present. 

 h. Flowers yellow. 



i. Leaves all radical: rays numerous 



and fertile 25. Tussilago 



ii. Leaves on stems, alternate. 



J. Heads small, in large clusters 



or panicles 26. Solidago 



jj. Heads large and broad: leaves 

 large on stem and in a basal 



clump 27. Inula 



HH. Flowers not yellow. 



I. Scales of the involucre unequal. . .28. Aster 



ii. Scales equal in length 29. Erigeron 



in. Scales in several rows, more or 



less leafy 30. Callistephus 



gg. Rays none. 



