880 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



26. Rays not sessile, nor persistent, nor becoming papery (28) . 



28. Involucre distinctly double, the outer phyllaries herbaceous, the 

 inner ones broader, longer, membranous (29) . 

 29. Inner phyllaries free 71. Coreopsis. 



29. Inner phyllaries connate about to the middle, or higher. 



74. Thelesperma. 

 28. Involucre not double (30) . 



30. Plant a scapose perennial, with broad silvery-pubescent entire 



leaves and very large solitary heads 67. Enceliopsis. 



30. Plants leafy-stemmed; leaves and heads otherwise (31). 



31. Achenes conspicuously ciliate on the margin, notched at apex, 



very flat; plants shrubby 64. Encelia. 



31. Achenes not conspicuously ciliate on the margin (32). 



32. Achenes 2-winged 70. Verbesin a. 



32. Achenes not 2-winged, sometimes acutely margined (33). 

 33. Leaves pinnately parted or dissected__ 57. Ratibida. 

 33. Leaves entire to merely toothed or 3-lobed (34). 



34. Achenes very flat, notched at apex _' _ _ 65. Simsia. 



34. Achenes more or less thickened, not notched at apex (35) . 

 35. Leaves alternate, ovate, often 3-lobed; rays pistillate. 



58. Zaluzania. 



35. Leaves opposite at least below, lance-ovate to linear; 



rays neutral 61. Viguiera. 



H. Hermaphrodite flowers with a tubular, regular or nearly regular corolla; rays 

 evident but sometimes small; pappus present, of awns, squamellae, cr 

 paleae, these sometimes united into a crown. 



1. Receptacle paleaceous (2) . 



2. Rays white, pink, or purple (3). 



3. Rays fertile, the disk flowers sterile; achenes with a narrow caUous margin, 

 this adnate at base to the pales of the 2 opposed disk flowers and to 

 the subtending phyllary, at length tearing away from the achene 



below but remaining attached at apex 43. Parthenium. 



3. Rays and disk flowers all fertile (4). 



4. Pappus of 10 bristlelike hairy awns, the hairs on their outer side straight, 



on the inner side entangled into a woolly mass 80. Layia. 



4. Pappus otherwise (5) . 



5. Rays sessile and persistent on their achenes (6). 



6. Involucre strongly graduated; pales of the receptacle not cuspidate. 



52. Zinnia. 



6. Involucre not distinctly graduated; pales of the receptacle cuspidate. 



53. Sanvitalia. 

 5. Rays not sessile and persistent on their achenes (7). 



7. Leaves merely toothed (8). 



8. Rays numerous and very narrow; leaves sessile or subsessile. 



55. Eclipta. 



8. Rays 5 or fewer, short and broad; leaves petioled. 



78. Galinsoga. 

 7. Leaves dissected (9) . 



9. Achenes beaked ; plant glabrous 76. Cosmos. 



9. Achenes not beaked; plant more or less woolly. 



107a. Leucampyx. 

 2. Rays yellow, or partly purple brown (10). 



10. Rays fertile, the disk flowers sterile; achenes of the rays adnate at base 

 to the subtending phyllary and to the pales of the opposed outer 



disk flowers, the whole falling away together 42. Engelmannia. 



10. Rays and disk flowers all or mostly fertile, or the rays infertile, or else 

 (genus Hemizonia) the ache>nes of the rays not as in genus Engelman- 

 nia (11). 

 11. Rays persistent on their achenes, becoming papery. _ 52. Zinnia. 

 11. Rays not persistent or papery (12). 



12. Involucre distinctly double, the outer phyllaries narrow, herbaceous, 

 the inner ones broader, membranous (13). 

 13. Inner phyllaries connate to the middle, or higher. 



74. Thelesperma. 

 13. Inner phyllaries free essentially to the base (14). 



14. Pappus not of retrorsely hispid awns 71. Coreopsis. 



14. Pappus of retrorsely hispid awns (15). 



