300 COMPOSITAE. [Vol. III. 



Achcnes fusiform, terete; annual herbs with small heads. 28. Chaetopappa. 



Achenes obovate, flattened, with thickened or winged marKins; perennials. 29. Bollonia. 

 ■5f -Jf Pappus of numerous capillary bristles. 

 I. 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. SeHcocarpus. 



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

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



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



32. I.eucelene. 

 Involucre turbinate; rays not exceeding the mature pappus, or none. t,^. K>achyactis. 



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



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

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



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



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

 Leaves lanceolate, ovate, or obovate; rays white. 37. Doelliitgeria. 



Leaves narrowly linear; rays violet. 38. lanaclis. 



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



Tribe 4. Inulkae. 



■^ Heads small, rays none; flowers white, or whitish. 



1 . Receptacle chalTy. 



Receptacle convex; pappus none. 40. Filat;o. 



Receptacle subulate; pappus of the inner flowers of rough capillary bristles. 41. UiJ'ola. 



2. Receptacle naked. 



a. Pappus, at least that of pistillate flowers, of capillar)- bristles. 



Bracts of the involucre not scarious; plants pubescent orglabrous, notwooUy. 42. Pluchea. 

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

 Plants dioecious, or polygamo-dioecious. 



Pappus-bristles of stam-'nate flowers thickened above. 43. Anlennaria. 



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



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



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



-X- -X- Heads large; ray-flowers yellow. ^y. Inula. 



Tribe 5. Hellvntheae. 

 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. Me I am podium. 



Achenes flattened. 



Ray-flowers in 2 or 3 series; achenes falling away free. 50. Silfi/iium. 



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

 "* Rays large, yellow. 



Leaves opposite and basal. 51. Clirysogonum. 



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. Parllienium. 



B. Disk-flowers fertile. 

 i^ Ray-flowers persistent upon the achenes. 

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



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



^ ^ Ray-flowers deciduous, or none.* 

 t Pappus a cup, or crozcii, or of a feiv leelli, awns, or bristles. 

 I. Achenes, at least those of disk-flowers, not compressed (except in Ralibida and I'erbesina); 



scales of the receptacle mostly concave, or clasping. 

 Scales of the receptacle small, awn-like or bristles-like; rays white, short. 57. Eclipta. 

 Scales of the receptacle broad, larger. 



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



Involucre of several or numerous separate bracts. 

 Receptacle conic, or columnar. 



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



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

 Rays yellow. 



Achenes 4-angled. 60. Rudheckia. 



Achenes compressed, winged. 61. Ratibida. 



Rays rose-purple. 62. Brauneria. 



Receptacle flat, or convex (low-conic in species of Nos. 64 and 65. 1 



Low flesliy sea-coast shrubs. 63. Borrichia. 



Tall herbs, not fleshy. 



.\chenes not much flattened, not winged, nor margined. 64. Helianthus. 



Achenes of disk-flowers flattened and margined, or winged. 65. I'erbesina. 

 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, upwardly or downwardly barbed or hispid 67. Bidens. 



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

 1 1 Pappus 0/ numerous .wales. 

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



Leaves alternate, entire. 



