1474 CONTEIBUTIONS FROM THE NATIONAL HERBARIUM 



Outer phyllaries not caudate; leaves otherwise. 

 Leaves mostly rhombic-ovate, coarsely toothed. 



21. C. laciniatus. 

 Leaves ovate to suborbicular, crenate-serrate. 



Heads 8 to 18-flowered, 3 to 5 mm. thick; leaves ovate, on 



petioles usually about 1 cm. long 22. C. calif ornicus. 



Heads 18 to 62-flowered, 6 to 11 mm. thick; leaves suborbicular 



or reniform, short-petioled 23. C. veronicaefolius. 



Involucre 12 to 14 mm. high 24. C. palmeri. 



Leaves narrower, ovate to oblong or elliptic, 2 to 15 cm. long. 



Phyllaries slightly graduate, the outermost subherbaceous or foliace- 

 ous, from half as long as the inner to longer. 



Leaves softly tomentose beneath 40. C. pacayensis. 



Leaves puberulous to nearly glabrous beneath. 



41. C. fioribundus. 

 Phyllaries strongly graduate, the outermost very short. 

 Achenes 3 to 3.7 mm. long. 



Leaves elliptic-ovate to rhombic-ovate. 



Heads subsessile, glomerate 25. C. glomeratus. 



Heads mostly pedicellate. 



Inflorescence dichotomous; phyllaries obtuse. 



26. C. hebecarpus. 

 Inflorescence paniculate, elongate; phyllaries acute. 



27. C. nelsonii. 

 Leaves suborbicular-ovate to deltoid-ovate. 



Leaves suborbicular-ovate; outer phyllaries with subsquarrose 



tips 28. C. paniculatus. 



Leaves deltoid-ovate; outer phyllaries not subsquarrose-tipped. 



Inner phyllaries acute 29. C. secundiflorus. 



Inner phyllaries obtuse 30. C. parryi. 



Achenes 4 to 5.5 mm. long. 



Middle and usually also the inner phyllaries obtuse, sometimes 

 mucrouate. 

 Leaves coriaceous or thick ish. 

 Leaves deltoid-ovate. 



Outermost phj-llaries ovate-lanceolate, acutish. 



30. C. parryi. 

 Outermost phyllaries broadly oval, rounded. 



31. C. tomentellus. 



Leaves lanceolate 32. C. lancifolius. 



Leaves thin, membranaceous 33. C. orizabaensis. 



Middle and inner phyllaries acute or acuminate. 



Leaves oblong-ovate to ovate-lanceolate. Pedicels densely 



glandular 34. C. pendulus. 



Leaves ovate to suborbicular-ovate. 

 Leaves ovate, chartaceous. 



Heads secund-racemose 35. C. seemannii. 



Heads thyrsoid 36. C. saltillensis. 



Leaves deltoid-ovate to suborbicular-ovate, never char- 

 taceous. 

 Inflorescence loose, the cymes strongly nodding. 



37. C. squarrosus. 

 Inflorescence rather dense, the cymes erect or slightly 

 nodding. 



Leaves membranaceous 38. C. botterii. 



Leaves subcoriaceous or firm 39. C. adenocarpus. 



