91 6 FLORA. 



Plants not dioecious ; flowers all fertile. 45. Gnaphalium. 



b. Pappus none; leaves broad, alternate, woolly beneath. 46. Adenocaulon. 



* Heads large; ray-flowers yellow. 47 Inula. 



Tribe 5. HELIANTHEAE. 



A. Disk-flowers perfect, but sterile. 



Achenes thick, short, not flattened; pappus none. 



Achenes merely subtended by the inner involucral bracts. 48. Polymnia. 



Achenes embraced and enclosed by the inner involucral bracts. 



49. Melampodium. 

 Achenes flattened. 



Ray-flowers in 2 or 3 series; achenes falling away free. 50. Silphium. 



Ray-flowers in i series; achenes adnate to 2 or 3 scales of the receptacle, falling away 

 with them. 



Rays large, yellow. 



Leaves opposite and basal. 51. Chrysogonum. 



Leaves alternate. 



Pappus none, or of 2 caducous awns. 52. Berlandiera. 



Pappus a persistent irregularly-cleft crown. 53. Engelmannia. 



Rays small, the heads appearing discoid. 54. Parthenium. 



B. Disk-flowers fertile. 



Ray-flowers persistent upon the achenes. 



Achenes compressed, or 3-angled; leaves entire. 55. Crassina. 



Achenes short, thick; leaves toothed. 56. Heliopsis. 



* Ray-flowers deciduous, or none. 



f Pappus a cup, or crown, or of a few teeth, awns, or bristles, 

 i. Achenes, at least those of disk-flowers, not compressed (except in Ratibida and Ver- 



besina); scales of the receptacle mostly concave, or clasping. 

 Scales of the receptacle small, awn-like or bristle-like; rays white, short. 



57. Eclipta. 

 Scales of the receptacle broad, larger. 



Involucre of 4 large somewhat united bracts. 58. Tetragonotheca. 



Involucre of several or numerous separate bracts. 

 Receptacle conic, or columnar. 



Ray-flowers fertile, or wanting; leaves opposite. 59. Spilanthes. 



Ray-flowers sterile, or neutral; leaves mostly alternate. 

 Rays yellow. 



Achenes 4-angled. 60. Rudbeckia. 



Achenes compressed, winged. 61. Ratibida. 



Rays rose-purple. 62. Brauneria. 



Receptacle flat, or convex (low-conic in species of Nos. 64 and 65;. 



Low, fleshy seacoast shrubs. 63. Borrichia. 



Tall herbs, not fleshy. 



Achenes not much flattened, not winged, nor margined. 



64. Helianthus. 

 Achenes of disk-flowers flattened and margined, or winged. 



65. Verbesina. 



2. Achenes very flat; scales of the receptacle flat, or but slightly concave. 



a. Bracts of the involucre all separate. 



Pappus of 2 short teeth or awns, or a mere border, 'or none. 66. Coreopsis. 



Pappus of 2-6 awns or teeth, ^pwardly or downwardly barbed or hispid. 



67. Bidens. 

 b. Inner bracts of the involucre united to about the middle. 



68. Thelesperma. 

 t t Pappus of numerous scales. 



Leaves opposite, toothed; ray-flowers fertile; rays small. 69. Galinsoga. 

 Leaves alternate, entire. 



Rays large, neutral ; receptacle deeply honeycombed. 70. Actinospermum. 



Rays none; scales of the receptacle narrow, rigid. 71. Marshallia. 



