1424 CONTEIBUTIONS FROM THE NATIONAL HERBARIUM 



12. STEVIA Cav. Icon. PL 4: 32. 1797. 

 Shrubs or herbs, often glutinous, with mostly opposite leaves; heads small, 5 to 

 8-flowered (in all the following species), corymbose-panicled; phyllaries 5 to 8, 

 subequal, stiffish, subherbaceous; corollas all tubular, slender, white or purplish; 

 achenes slender, usually 5-ribbed, glabrous or hispidulous; pappus of 2 to 12 

 short squamellae, or slender awns, or both. 



Leaves more or less densely griseous-pubescent to canescent-tomentose beneath. 

 Leaves 2.5 cm. long or less; involucre densely canescent-tomentulose. 



1. S. tephrophylla. 

 Leaves 2.5 cm. long or more; involucre green, rarely griseous-tomentellous. 

 Leaves obscurely petioled, lance-linear, entire, densely canescent-tomentose 



beneath 2. S. revoluta. 



Leaves distinctly petioled, lanceolate to ovate, almost always toothed, grise- 

 ous-pubescent or puberulous beneath. 

 Hairs of branches and leaves mostly glandular-capitate. 



3. S. glandulosa. 

 Hairs of branches and leaves not glandular-capitate. 



Involucre griseous-tomentellous, 4 mm. high; leaves ovate or ovate- 

 elliptic; petioles 3 to 7 mm. long 4. S. dictyophylla. 



Involucre merely griseous-pilosulous or griseous-pubescent; leaves 

 oblong-ovate to lance-ovate or lance-oblong; petioles usually 8 to 



25 mm. long 5. S. subpubescens. 



Leaves glabrous or sparsely pubescent beneath. 



Leaf blades oval-ovate, obtuse, coarsely crenate, 3.2 cm. long or less, nearly 



as wide as long 6. S. berlandieri. 



Leaf blades linear to ovate or oval-ovate, usually acute, much longer than wide. 

 Leaves with all veins (including the secondaries) strongly prominulous- 

 reticulate especially beneath. 



Pappus of awns and squamellae 7. S. nervosa. 



Pappus of short squamellae only. 



Stem and leaves pubescent 8. S. madrensis. 



Stem and leaves glabrous. 



Heads in very dense subglobose glomerules solitary at tips of stem 

 and branches of inflorescence; leaves 8 to 14.5 cm. long, their 



teeth acute 9. S. phlebophylla. 



Heads densely corymbose-paniculate, not glomerate; leaves 7 cm. 

 long or less. 

 Leaves obtuse to acute, 13 mm. wide or less; petioles 3 mm. long 



or less 10- S. venosa. 



Leaves acuminate, 25 to 30 mm. wide; petioles 20 mm. long. 



11. S. nitida. 

 Leaves obscurely veined, or at least with the secondaries not prominulous. 

 Leaves linear to narrowly lanceolate, 1 cm. wide or less. 



Leaves linear or linear-oblanceolate, obtuse, entire, 4 cm. long and 



4 mm. wide, or smaller; heads few 12. S. collodes. 



Leaves linear to narrowly lanceolate, acuminate, often toothed, usually 

 6 to 8 cm. long. 

 Leaves linear-filiform to very narrowly linear-lanceolate, entire or 



sharply toothed, 0.8 to 4 mm. wide 13. S. stenophylla. 



Leaves narrowly lanceolate or linear-lanceolate, usually serrulate, 



usually 5 to 10 mm. wide 14. S. salicifolia. 



Leaves lanceolate to ovate or oval-ovate, rarely less than 1 cm. wide. 

 Young branches white-lanate, becoming arachnoid, finally glabrate. 



15. S. seleriana. 



