STANDLEY TREES AND SHRUBS OF MEXICO 1573 



Heads on peduncles 2 cm. long or less; leaf blades rhombic-ovate, 

 widest near middle, about 10 cm. long.. 17. V. intermissa. 

 Leaves green or griseous-pubescent beneath. 



Leaves lanceolate to oval-ovate, narrowed to both ends from near the 

 middle. 



Leaves sessile, entire 21. V. petrophila. 



Leaves petioled, serrate or serrulate. 



Leaves griseously subtomentose-pilose beneath; disk in anthesis 



about twice as high as thick 16. V. sorona. 



Leaves merely puberulous, strigillose, or strigose beneath; disk in 

 anthesis as thick or thicker than high. 



Involucre 7 to 8 mm. high 17. V. intermissa. 



Involucre 3 to 5 mm. high 22. V. liebmannii. 



Leaves chiefly ovate, broad at base or only shortly cuneate. 



Leaves sessile or subsessile, or on short, broadly winged, clasping 

 petioles. 

 Leaves on broadly winged auriculate-clasping petioles. 



7. V. palmeri. 

 Leaves sessile or subsessile. 



Leaves chiefly obovate; disk about 1 cm. thick. 



21. V. petrophila. 

 Leaves ovate; disk more than 1 cm. thick. 



Leaves entire or subentire 6. V. dissita. 



Leaves coarsely toothed 10. V. peninsularis. 



Leaves slender-petioled. 



Leaves dull green, not conspicuously reticulate; phyllaries linear 



to lanceolate 12. V. chihuahuensis. 



Leaves bright green, conspicuously reticulate on both sides; 



phyllaries oval to obovate 13. V. hastata. 



Lamina of the rays less than 1 cm. long. 



A. Stem more or less winged, or else leaves auriculate at base. 

 Stem wingless; leaves auriculate at base. 



Leaves entire or subentire, canescent-tomentose beneath, lanceolate. 



25. V. potosina. 

 Leaves serrate or serrulate, usually green beneath. 



Leaves abruptly contracted into broadly winged auriculate-am- 



plexicaul petioles , 7. V. palmeri. 



Leaves gradually narrowed to base. 



Leaves distinctly petioled, the petioles with deciduous auricles at 

 base. 

 Leaves strigillose to pilose beneath, chiefly on the veins; pales 

 with spreading or reflexed cuspidate tips. 



22. V. liebmannii. 

 Leaves tomentose-pilosulous beneath; pales blunt or with short 



erect mucros 31. V. oncophora. 



Leaves sessile or subsessile. 



Leaves distinctly pubescent or tomentose beneath. 

 Leaves 2.5 to 15 cm. long, 0.8 to 2.5 cm. wide. 



Leaves about 4 cm. long, acute 15. V. hypoleuca. 



Leaves 5 to 15 cm. long, attenuate 26. V. oreopola. 



Leaves 18 to 27.5 cm. long, 5 to 11 cm. wide. 



27. V. auriculata. 

 Leaves glabrous or sparsely strigillose on the costa beneath. 



Leaves oblong, 3.7 to 5 cm. wide... 23. V. nelsonii. 



Leaves lanceolate, 1 to 1.3 cm. wide ..24. V. otophylla. 



