CAEDUACEAE. 



285 



Involucre of 5-6 series of bracts : ligules of 

 the ray violet, or rarely white: achenes nar- 



leaf-blades 1-ribbed. 18 



IONACTIS. 

 BACCHARIS. 



Heads with dioecious flowers : ray-flowers wanting. 19. 



TRIBE IV. INULEAE. 



Ray-flowers wanting : disk-flowers with white or whitish co- 



rollas : heads relatively small. 



Receptacle chaffy : involucre of few bracts. 20. GIFOLA. 



Receptacle naked: involucre of many bracts. 

 Plants dioecious or polygamo-dioecious. 



Pappus-bristles of the staminate flowers thickened 



above : plants stoloniferous. 21. ANTENNARIA. 



Pappus-bristles not thickened : plants not stolon- 



iferous. 22. ANAPHALIS. 



Plants not dioecious : flowers all fruit-producing. 23. GNAPHALIUM. 



Ray-flowers present ; corollas yellow : heads relatively large. 24. INULA. 



TRIBE V. HELIANTHEAE. 



Disk-flowers perfect, but not fruit-producing. 



Achenes short, thick or turgid : pappus wanting. 



Achenes obcompressed, 3-ribbed. 25. 



Achenes laterally compressed, closely striate. 26. 



Achenes markedly flattened : pappus present, sometimes 



obsolete. 

 Ray conspicuous ; ligules yellow, spreading : heads 



mostly showy. 

 Ray-flowers in 2 or 3 series : achenes falling away 



free. 27. 



Ray-flowers in 1 series : achenes adnate to 2 or 3 



bractlets and falling away with them. 28. 



Ray inconspicuous ; ligules white or whitish, erect or 



nearly so : heads not showy. 29. 



Disk-flowers fruit-producing. 



Corollas of the ray persistent on the achenes. 30. 



Corollas of the ray deciduous, or wanting. 



Pappus a mere crown or a cup, or of few teeth, awns, 



or bristles. 



Achenes, at least those of the disk, not compressed : 

 bractlets of the receptacle mostly concave or 

 clasping. 



Bractlets of the receptacle mere chaffy subulate 

 awns or bristles : ray-flowers with white 

 ligules. 31. 



Bractlets of the receptacle broad, concave or 



clasping. 



Receptacle conic to columnar. 32. 



Receptacle flat or convex. 



Achenes not much flattened, wingless, 



erect : leaves not decurrent. 

 Achenes flattened, winged, widely spread- 



ing : leaves decurrent. 

 Achenes very flat : bractlets of the receptacle flat 



or at least not clasping. 



Pappus of 2 fimbriolate awns, scales of teeth, or 

 a mere border or obsolete. 



POLYMNIA. 

 POLYMNIASTRUM. 



SILPHIDM. 

 CHRYSOGONUM. 

 PARTHENIDM. 

 HELIOPSIS. 



33. 

 34. 



VERBESINA. 

 RDDBECKIA. 



HELIANTHUS. 

 RIDAN. 



35. COREOPSIS. 



Pappus of 2-6 awns or teeth, upwardly or 



downwardly barbed or hispid. 

 Pappus of numerous scales. 



36. 

 37. 



BIDENS. 

 GALINSOGA. 



TRIBE VI. HELENIEAE. 



A single genus in our range. 



38. HELENIDM. 



TRIBE VII. ANTHEMIDEAE. 

 Receptacle chaffy. 



Heads small : involucre not flattened, obovoid to campanu- 



late : achenes flattened. 39. ACHILLEA. 



Heads large : involucre depressed, hemispheric : achenes 



terete or angled. 40. ANTHEMIS. 



Receptacle naked or sometimes merely pubescent. 



Ray-flowers normally present. 41. CHRYSANTHEMUM. 



Ray-flowers wanting. 42. TANACETUM. 



