STANDLEY TEEES AND SHRUBS OF MEXICO 1411 



Heads 1 to 11-flowered; involucre 3 to 7 mm. high. 



Heads 7 to ll-fiowered; inner phyllaries not deciduous (except in no. 17). 



Leaves floccose-tomentose beneath 14. V. oaxacana. 



Leaves not floccose-tomentose beneath. 



Leaves scabrous-pubescent on the veins beneath. 



15. V. capreaefolia. 

 Leaves puberulent or sordid-pilosulous beneath. 

 Leaves 1.5 to 2 cm. wide; ph3'llaries purple-tipped. 



16. V. liatroides 



Leaves 3.2 to 5.7 cm. wide; phyllaries whitish 17. V. littoralis. 



Heads 1 to 5-flowered; inner phyllaries deciduous. 

 Heads 1 or 2-flowered, 



Phyllaries (at least the middle and outer) distinctly mucronate. 

 Leaves chiefly oval or obovate; mucros of the middle and outer 



phyllaries about 0.2 mm. long 18. V. mucronata. 



Leaves chiefly broadly ovate; mucros of the middle and outer 



phyllaries about 0.5 mm. long 19. V. aristifera. 



Phyllaries not mucronate, sometimes apiculate. 



Leaves densely canescent or cinereous-tomentose beneath. 



Leaves broadly ovate or oblong-ovate, rounded or cordate at 



base, 2 to 7 cm. wide 20. V. monosis. 



Leaves elliptic-oblong or oval-oblong, cuneate at base, 1.5 to 

 4 cm. wide. 

 Inner phyllaries acute or acuminate. 



21. V. tarchonanthifolia. 



Inner phyllaries obtuse or rounded 22. V. obtusa. 



Leaves not densely tomentose beneath. 



Leaves oval-ovate or broadly ovate, 3 to 4 cm. wide. 



23. V. steetzii. 

 Leaves elliptic, 2.5 cm. wide or less. 



Leaves tufted in the axils of the veins beneath; phyllaries 



usually tomentose at apex 24. V. salicifolia. 



Leaves not tufted in the axils of the veins beneath; phyllaries 



not tomentose at apex 25. V. pallens. 



Heads 3 to 5-flowered. 



Leaves very densely tomentose over whole surface beneath. 

 Phyllaries densely tomentose; achenes glabrous. 



Achenes whitish or light brown 26. V. leiocarpa. 



Achenes dark brown or purplish brown 27. V. melanocarpa. 



Phyllaries not densely tomentose; achenes pubescent. 

 Leaves ovate, less than twice as long as wide. 



28. V. durangensis. 

 Leaves elliptic to oval-lanceolate, more than twice as long as 

 wide. 

 Leaves 6.5 to 7.3 cm. long, less than three times as long as wide. 



29. V. oolepis. 

 Leaves 7 to 19 cm. long, more than three times as long as wide. 



30. V. palmeri. 

 Leaves not denselj^ tomentose over whole surface beneath. 

 Leaves densely pilosulous at least along the costa beneath. 



Leaves elliptic or oblong-elliptic; phyllaries obtuse to acutish, not 

 apiculate 30. V. palmeri. 



