COMPOSITES 433 



EE. Foliage leaves entire, toothed, or broad- 

 lobed. 



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



FF. Achenes straight. 



o. Torus flat or slightly convex 15. Chrysanthemum 



GO. Torus conical. 



H. Rays yellow: flowers large, 2-3 in... 16. Rudbeckia 

 HH. Rays not yellow: flowers about 



1 in. across: plant low 17. Bellis 



oc. 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 



cocc. Pappus of many bristles. 



D. Plant very prickly 22. Cvrsium 



DD. Plant not prickly. 



E. Involucre prickly and bur-like x.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 



GO. Rays none. 



BB 



