WOOTON AND STANDLEY PLOEA OF NEW MEXICO. Y41 



KEY TO THE SPECIES. 



Annual 1. S. vulgaris. 



Perennials. 

 Heads discoid. 



Heads small, 7 to 10 mm. high. 

 Glabrous; leaves linear to linear-oblanceolate, entire or 



nearly so 2. »?. pudicus. 



Slightly tomentose; leaves cordate-ovate to oblong- 

 lanceolate, coarsely toothed 3. *?. sacramentanus. 



Heads large, 12 to 20 mm. liigh. 

 Leaves long-villous on the midrib beneath; heads usually 



racemose 4. 8. scopulinus. 



Leaves not long-villous; heads not racemose. 

 Plants more or less tomentose; leaves thick and fleshy. 5. S. chloranthus. 

 Plants glabrous; leaves thin. 

 Leaves coarsely and irregularly laciniate-serrate, 

 abruptly contracted at the base, mostly petio- 



late 6. S. bigelovii. 



Leaves finely and evenly serrate, attenuate to the 



very short petiole, or sessile 7. 8. rushyi. 



Heads radiate. 



Plants densely viscid 8. S. parryi. 



Plants not viscid. 

 Leaves or their divisions narrowly linear or linear-filiform. 



Plants permanently tomentose 9. S. filifolius. 



Plants glabrous. 

 Leaves entire, rarely with a pair of short filiform 



lobes at the base 10. S. spartioides. 



Leaves, except the uppermost, pinnately divided. 



Heads campanulate ; bracts 12 to 15 11 . 8. riddellii. 



Heads cylindric or nearly so; bracts 8 to 10 12. S. multicapitatus. 



Leaves neither linear-filiform nor with linear-filiform 

 divisions. 

 Heads nodding. 

 Plants low, not more than 10 cm. high; leaves obo- 



vate-orbicular, purplish 13. S. taraxacoides. 



Plants taller, 50 cm. high; leaves lanceolate or 



oblanceolate, not purplish 14. S. amplectens. 



Heads not nodding. 

 Heads solitary. 

 Stems and leaves densely tomentose; stems with 



only a few much reduced leaves 15. S. actinella. 



Stems and usually the leaves glabrate; stems 



leafy 16. S. mogoUonicus. 



Heads not solitary, except in depauperate speci- 

 mens. 

 Plants equally leafy throughout. 

 Leaves pinnatifid or pinnate. 

 Leaves pinnate, the terminal lobe orbicular 



or semiorbicular, obtusely toothed 17. S. sanguisorboides. 



Leaves pinnatifid, all the segments lanceolate 

 or naiTower, with acute teeth. 

 Involucre 7 mm. high; leaves shallowly 



pinnatifid, with broad segments 18. S. anibrosioides. 



