300 



COMPOSITAE. 



[Vol. III. 



28. Chaetopappa. 



29. Boltonia. 



Achenes fusiform, terete; annual herbs with small heads. 

 Achenes obovate, flattened, with thickened or winged margins; perennials. 



Sf -X- Pappus of numerous capillary bristles. 

 1. Pappus a single series of capillary bristles; sometimes with an outer series of shorter ones. 



a. Bracts of the involucre in 2 to many series. 

 Bracts mostly in 2-5 series; teeth or lobes of the leaves not bristle tipped. 



Involucre narrow, its bracts firm; rays few, white. 30. Sericocarpus. 



Involucre turbinate to hemispheric, bracts mostly thin; rays usually numerous, white to purple. 

 Disk-flowers turning red, purple, or brown. 31. Aster. 



Disk-flowers permanently white; leaves subulate to spatulate, crowded, rigid. 



32. Leucelene. 

 Involucre turbinate; rays not exceeding the mature pappus, or none. ^. Brachyactis. 



Bracts in many series; teeth or lobes of the leaves bristle-tipped in our species. 34. Mackaeranthera. 



b. Bracts of the involucre in only 1 or 2 series, very narrow; heads mostly long-peduncled. 

 Rays longer than the diameter of the disk. 35. Erigeron. 



Rays not longer than the diameter of the disk; heads very small, panicled. 36. Leptilon. 



2. Pappus distinctly double, the inner bristles long, the outer shorter, 

 leaves lanceolate, ovate, or obovate; rays white. 37. Doellingeria. 



Leaves narrowly linear; rays violet. 38. lanaclis. 



C. Ray-flowers none ; dioecious shrubs ; pappus capillary. 39. Baccharis. 



Tribe 4. InulEAE. 



X- Heads small, rays none ; flowers white, or whitish. 



1. Receptacle chaffy. 



Receptacle convex; pappus none. 40. Eilago. 



Receptacle subulate; pappus of the inner flowers of rough capillary bristles. 41. Gifola. 



2. Receptacle naked. 



a. Pappus, at least that of pistillate flowers, of capillary bristles. 



Bracts of the involucre not scarious; plants pubescent or glabrous, not woolly. 42. Pluchea. 

 Bracts of the involucre scarious, mostly white or pink; plants woolly. 

 Plants dioecious, or polygamo-dioecious. 



Pappus-bristles of stanrnate flowers thickened above. 43. Antennaria. 



Pappus-bristles not thickened; stem leafy. 44. Anaphalis. 



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



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



-X- & 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. 

 Achenes embraced and enclosed by the inner involucral bracts. 

 Achenes flattened. 



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



Ray-flowers in 1 series; achenes adnate to 2 or 3 scales of the receptacle, falling away with them. 

 Rays large, yellow. 



Leaves opposite and basal. 

 Leaves alternate. 



Pappus none, or of 2 caducous awns. 

 Pappus a persistent irregularly cleft crown. 

 Rays small, the heads appearing discoid. 



B. Disk-flowers fertile. 

 .}f Ray-flowers persistent upon the achenes. 

 Achenes compressed, or 3-angled; leaves entire. 

 Achenes short, thick; leaves toothed. 



X- -X- Ray-flowers deciduous, or none." 

 t Pappus a cup, or crown, or of a few teeth, awns, or, bristles. 

 1. Achenes, at least those of disk-flowers, not compressed (except in Ratibida and Verbesina) 



scales of the receptacle mostly concave, or clasping. 

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

 Scales of the receptacle broad, larger. 



Involucre of 4 large somewhat united bracts. 

 Involucre of several or numerous separate bracts. 

 Receptacle conic, or columnar. 



Ray-flowers fertile, or wanting; leaves opposite. 

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

 Rays yellow. 



Achenes 4-angled. 

 Achenes compressed, winged. 

 Rays rose-purple. 

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

 Low fleshy sea-coast shrubs. 

 Tall herbs, not fleshy. 



Achenes not much flattened, not winged, nor margined. 

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

 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. 



Pappus of 2-6 awns or teeth, upwardly or downwardly barbed or hispid. 67. 



b. Inner bracts of the involucre united to about the middle. 68. 

 1 1 Pappus of numerous scales. 

 Leaves*?>pposite, toothed; ray-flowers fertile ; rays small. 69. Galinsoga. 



Leaves alternate, entire. 



48. Polymnia. 



49. Melampodium. 



51. Clirysogonutn. 



52. 

 53- 



54- 



55- 

 56. 



57- 

 53. 



Berlandiera. 

 Engelm a n n ia 

 Partlienium. 



Crassina. 

 Heliopsis. 



Eclipta. 



Tet rago notheca. 



59. Spilanlhes. 



60. 

 61. 

 62. 



Rudbeckia. 



Ratibida. 



Brauneria. 



65. Borrichia. 



64. 

 65- 



Helianthus. 

 Verbesina. 



Coreopsis. 

 B 1 dens. 

 Tlielesperma. 



