1638 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM 



Outer phyllaries broad, two-thirds as long as the inner. 



5. T. pterocaulis. 

 Leaves not decurrent (sometimes sUghtly so in T. rugulosa, T. megalophylla, 

 and T. wrightii). 

 Outer phyllaries ovate, large, usually exceeding the inner. _ 6. T. longifolia. 

 Outer phyllaries linear to narrowly ovate, usually much shorter than the inner- 

 Leaves glabrous or nearly so beneath, sometimes glandular. 

 Leaves conspicuously glandular beneath. 



Inflorescence appressed-pubescent 16. T. calif ornica. 



Inflorescence spreading-villous 17. T. silvatica. 



Leaves not glandular beneath. 



Outer phyllaries Hnear or lance-linear 18. T. radialis. 



Outer phyllaries spatulate to oval-obovate 19. T. wrightii. 



Leaves silky-pubescent or tomentose beneath. 



Inner phyllaries 5; heads 5 to 7-flowered 7. T. oligantha. 



Inner phyllaries 8; heads 10 to 25-flowered. 



Larger leaves narrowly lanceolate or linear-lanceolate, usually 1 cm 

 wide or less. 

 Heads small, about 1.3 cm. high; leaves not revolute. 



8. T. hyposericea. 

 Heads larger, 1.5 to 2 cm. high; leaves usually strongly revolute. 

 Leaves 6 to 12 mm. wide, silky-tomentose beneath __9. T. pringlei- 

 Leaves usually 2 to 5 mm. wide, silky-pilose beneath. 



10. T. angustifolia* 

 Larger leaves lanceolate or lance-oblong, more than 1 cm. wide. 



Involucre subcanescently silky-pubescent 11. T. haenkei. 



Involucre green. 



Inflorescence conspicuously glandular 13. T. megalophylla. 



Inflorescence pubescent, not strongly glandular. 



Leaves merely apiculate, densely tomentose beneath. 



14. T. nelsonii. 

 Leaves gradually acuminate, silky-pubescent beneath. 



Leaves densely silky-pilose beneath 12. T. peninsularis. 



Leaves rather sparsely pilose beneath __16. T. rugulosa. 



1. Trixis decurrens DC. Prodr. 7: 68. 1838. 



Perdicium decurrens Sesse & Moc; DC. Prodr. 7: 68. 1838, as synonym. 



Known only from the type locality, Ayacapitla, Morelos. 



Stems several, sparsely branched; leaves lance-ovate, crowded, acuminate* 

 entire; heads terminal, subsolitary; outer phyllaries 5, ovate-lanceolate, the 

 inner 8. (Description compiled.) 



2. Trixis alata D. Don, Trans. Linn. Soc. 16: 192. 1830. 

 Guerrero; type from Mexico, without definite locality. 



Suffrutescent (?), densely stipitate-glandular and pilose, branched above, 

 very leafy; leaves oblong-ovate or lance-ovate, 5 to 8 cm. long, denticulate, sessile; 

 heads large, about 2 cm. high, crowded, leafy-bracted. 



3. Trixis calcicola Robinson, Proc. Amer. Acad. 49: 516. 1913. 



Known only from the type locality, Iguala Canyon, near Iguala, Guerrero. 



Shrubby, the branches broadly winged; leaves oblong, 10 to 14.5 cm. long, 

 2.3 to 3 cm. wide, acuminate, denticulate, glandular and puberulous; heads 

 crowded; outer phyllaries 1.7 cm. long, the inner 1.2 cm. 



4. Trixis mexicana Lex. in Llave & Lex. Nov. Veg. Descr. 1: 27. 1824. 

 Queretaro, Michoacdn, and Guerrero; type from Vallisoletum, Michoacdn. 

 Shrubby, "scandent"; stem broadly, branches narrowly winged; leaves short- 



petioled, the blades lance-ovate or oblong-ovate, 4 to 14 cm. long, denticulate. 



