WOOTON AND STANDLEY FLORA OF NEW MEXICO. 639 



Plants not spiny; leaves not scalelike. 



Leaves very thick and rigid, spinose-too tiled. 



37. Herrickia (p. 686). 

 Leaves thin, not spinose-toothed. 

 Bracts broad, with a distinct keel or midvein, not at all 

 foliaceous; plants more or less glaucous. 

 ^ 36. Bucephalus (p. 686). 



Bracts mostly nan'ow, when broad neither keeled nor with 

 a prominent midvein; plants not glaucous. 



35. Aster (p. 682). 

 Rays yellow or wanting. 



Pappus none to coroniform, paleaceous, or of few rigid awns, never of numerous 

 capillary bristles. 

 Pappus of few deciduous stout awns; heads large, usually viscid. 



11. Grindelia (p. 653). 

 Pappus not of awns, rarely a few in some of the disk flowers, paleaceous or 

 wanting; heads various. 

 Pappus altogether wanting; rays short, not surpassing the disk corollas; 



perennial plant, woody at the base 12. Gymnosperma (p. 656). 



Pappus present but often obscure; rays much surpassing the disk corollas; 

 annuals or perennials. 

 Rays 12, 1 cm. long; pappus coroniform; plant annual; heads large, 



hemispheric : 13. Xanthocephalum (jj. 656). 



Rays 10 or less, less than 5 mm. long; pappus not coroniform; annuals or 

 perennials; heads small. 

 Only the ray flowers fertile; pappus in disk flowers of aristiform palese 



dilated at the base 14. Amphiachyris (p. 656). 



All or most of the disk flowers as well as those of the rays fertile; pappus 

 of numerous palese, those of the ray small. 



15. Gutierrezia (p. 656). 

 Pappus, at least in part, of numerous capillary bristles. 



Ray achenes usually without pappus, never with numerous bristles. 



16. Heterotheca (p. 658). 

 All achenes with j^appus of numerous capillary bristles. 



Pappus of 2 series, the inner of capillary bristles, the outer of scales or short 



bristles 17. Chrysopsis (p. 658). 



Pappus wholly of capillary bristles. 

 Rays wanting. 



Involucres narrowly turbinate; bracts arranged in vertical ranks; 



usually shrubs 18. Chrysothamnus (p. 660). 



Involucres broadly turbinate or hemispheric; bracts not in vertical 

 ranks; herbs. 

 Stigma tips obtuse; involucral bracts narrow, slightly imbricated. 



(Rayless species of) 33. Erigeron (p. 674). 

 Stigma tips acute; bracts broad or well imbricated or both. 

 Leaves with spine-tipped teeth; corolla tube slender. 



(Rayless species of) 19. Sideranthus (p. 663). 

 Leaves not with spine-tipped teeth; corolla dilated above. 



20. IsocoMA (p. 665). 

 Rays present. 



Shrub .• . . .21. Chrysoma (p. 666). 



Herbs. 



Leaves pinnately cleft, or the teeth spine-tipped, or both. 



19. Sideranthus (p. 663). 



