FLOWERING PLANTS AND FERNS OF ARIZONA 881 



15. Achenes dimorphous, the outer ones with a winged or callous 

 margin, the inner ones narrower, wingless, somewhat 

 beaked; leaves pinnately parted into 3 to 7 entire or few- 

 parted linear lobes 73. Heterosperma. 



15. Achenes not dimorphous, neither winged nor truly beaked. 



75. Bidexs. 

 12. Involucre otherwise (16). 



16. Achenes dorso-ventrally compressed, with a pectinate wing. 



72. COREOC'ARPUS. 



16. Achenes laterallv if at all compressed, not with a pectinate wing 

 (17). 

 17. Plant scapose, perennial, with broad entire densely silvery- 

 pubescent leaves 67. Exceliopsis. 



17. Plants not scapose; leaves not silvery-pubescent (18). 



18. Pales of the receptacle in a single series inside the rays, united 



into a toothed cup 79. Hemizoxia. 



18. Receptacle paleaceous throughout, the pales not united (19). 



19. Leaves, at least the lower ones, parted or pinnatelv divided 



(20). 



20. Pappus a short chaffy crown; upper leaves entire or 3- 



lobed 56. Rudbeckia. 



20. Pappus of 1 or 2 short awns or teeth and sometimes also 



with squamellae; leaves,, even the upper ones, pin- 



natifid 57. Ratibida. 



19. Leaves entire or merelv toothed (21). 



21. Rays pistillate (22)/ 



22. Pappus a conspicuous, more or less divided, chaffy 

 crown, often with 1 or 2 awns; leaves alternate. 



59. Wyethia. 

 22. Pappus of 1 or 2 awns and sometimes with a very short 



crown of more or less united squamellae; leaves 



usually opposite (23). 



23. Pappus of 2 awns and several short, more or less 



united, intermediate squamellae, or the latter 



obsolete; perennial herb, with opposite ovate 



subsessile leaves; achenes not with broad white 



wings 69. Zexmenia. 



23. Pappus of 1 or 2 awns, without squamellae; leaves 

 not oppo-ite and subsessile, or else the achenes 



with broad white wings 70. Verbesixa. 



21. Rays neutral (24). 



24. Achenes more or less thickened (25). 



25. Pappus of caducous awns or paleae (usually 2, 

 sometimes many); achenes pubescent. 



62. Heliaxthus. 

 25. Pappus of persistent awns and squamellae, or if 

 wanting, then the achenes glabrous (26). 

 26. Peduncle noticeably thickened below the head; 

 plant annual, with broad ovate leaves. 



60. Tithoxia. 

 26. Peduncle not thickened below the head; plants, 



if annual, with narrow leaves. 61. Viguiera. 

 24. Achenes strongly compressed, very flat (27). 



27. Achenes w>th 2 white wings; leaves opposite, at 



least the lower ones 70. Verbesixa. 



27. Achenes not winged but sometimes narrowly white- 

 margined; leaves usually alternate (28). 

 28. Achenes not conspicuously ciliate on the margin; 

 plants herbaceous perennials. 



68. Helianthella. 

 28. Achenes conspicuously long-ciliate on the margin; 

 plants not herbaceous perennials (29). 

 29. Shrubs; achenes with a narrow white margin, 

 no crown, and 1 or 2 weak awns. 



64. Kxcelia. 

 29. Annual; achenes with a conspicuous white 

 margin and crown, and 2 strong awns. 



66. Ger.vea. 



