1574 CONTKIBUTIONS FROM THE NATIONAL HEKBARIUM 



Stem winged. 



Leaves densely silky-tomentose beneath 30. V. mollis. 



Leaves not silky-tomentose beneath. 

 Leaves alternate. 



Leaves tomentose or tomentulose beneath. 



Leaves unlobed 28. V. acapulcensis. 



Leaves palmately 3-lobed 51. V. fastigiata. 



Leaves subglabrous to puberulent beneath. 



Involucre 2 mm. high; stem densely spreading-hispidulous. 



47. V. cymbipalea. 

 Involucre 3 to 6 mm. high; stem usually strigillose or erectish- 

 hispidulous. 

 Leaves oblong, 15 to 20 cm. long, 3.7 to 5 cm. wide. 



23. V. nelsonii. 

 Leaves much smaller. 



Petioles 2 to 15 mm. long; leaves usually rhombic-ovate. 



22. V. liebmannii. 

 Petioles very short or none; leaves lanceolate or lance- 

 oblong 32. V. virgata. 



Leaves chiefly opposite. 



Leaves unlobed; phyllaries mostly squarrose-tipped; disk 6 to 

 10 mm. thick or more. 



Leaves strigillose beneath 29. V. zanthochlora. 



Leaves hispidulous or pilosulous beneath. 



Leaves chieflj' ovate; disk in anthesis 1 cm. thick or more. 



3. V. sphaerocephala. 

 Leaves oblong-lanceolate; disk in anthesis about 6 mm. thick. 



4. V. langlassei. 

 Leaves usually 3-lobed or pinnatifid; phyllaries mostlj^ appressed; 

 disk 3 to 6 mm. thick. 

 Stem broadl}' winged; phyllaries mostly acute or acuminate. 



52. V. green mani. 

 Stem narrowly winged; phyllaries obtuse. 



53. V. montanoifolia. 

 AA. Stem wingless; leaves not.auriculate at base. 

 B. Leaves chiefly opposite. 



Leaves bright green, shining at least above, subcoriaceous. 



Young branches white-tomentose 8. V. oligocephala. 



Young branches not tomentose 13. V. hastata. 



Leaves usuallj- dull green, not subcoriaceous. 



Leaves trilobate; heads subcylindric in anthesis 54. V. trilobata. 



Leaves not trilobate; heads broader. 



Leaves lance-oblong, about 4 times as long as wide, griseous or 

 canescent beneath. 

 Leaves finely canescent-strigillose beneath. _ 18. V. hypoglauca. 

 Leaves tomentose or tomentulose beneath. 



Leaves tomentulose and prominently reticulate beneath. 



36. V. grayii. 

 Leaves tomentose and not prominentlj'^ reticulate beneath. 



37. V. molinaria. 

 Leaves chiefly ovate or lance-ovate, usually much less than 4 

 times as long as wide. 

 Heads solitary or few, on usually elongate peduncles. 



Branchlets white-tomentose at apex 8. V. oligocephala. 



