564 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Leaves hispiduluiis, ciiived: rays 



pale yellow 5. 



Leaves caneseeut-pu berulent , 



straight ; rays bright yellow 10. 



Rays not yellow. 



Leaves cleft or parted. 



Leaves parted into narrow lobes .... 9. 



Leaves merely 3 to 5-<'left 9 a. 



Leaves entire or merely ttM)tlu>d. 



Stems branched, leafy, usually bear- 

 ing several heads. 



Puln'scence long and densi^; 



rays blue, pink or white 4. 



Pubesc«'nce very short. 



Leaves linear-lanceolate, 3- 



nerved 0. 



Leaves iiliform or linear, 1- 



nerved 11. 



Stems simple, scapiform; head al- 

 ways solitary. 

 Leaves dentate, broadly spatu- 

 late. 



Involucre glandular; stems 



not producing offsets. ... 13. 

 Involucre glabrate; stems 

 producing rosulate off.sets. 15. 

 L«'aves entire; involucre not 

 glandular. 



Kays white, leavj^s linear- 

 lanceolate 8 



Kays violet. 



Involucre very woolly. 14. 

 Involucre hispidulous . 7. 

 Roots annual, fibrous; leaves toothed or lobed. • 



Stems dilfu.s«'ly i)ranched; rays pink KK) to 120. . . 17. 

 Stems eroct, branched above^^^ys white 40 to GO. . 18. 

 Rays very short or wanting. 



Plants low, root stout, perennial; heads solitary to 

 numerous. 

 Leaves ternately clef t or parted ; involucre hirsute. 9b. 

 Lt^aves linear or linear-spatulate, narrow; invo- 

 lucre villous 20. 



Plants tall; heads several to numerous. 



Kays wanting; heads cymose; leaves firm; root pe- 

 rennial 19. 



Kays present, short. 



Heads paniculate; involucre glabrous; root an- 

 nual 21. 



Heads corymbose; involucre hirsute at least 

 at base; roots biennial. 



Tall, 30 to 60 cm. ; heads many 22. 



Low 10 to 20 cm. ; heads few 22 a. 



E. curvifoliufi. 

 E.jUijolius. 



E. compositus. 



E. composilris trijidus. 



E. hispidissimus. 



E. cori/mhoiius. 

 E. linearis 



E. leihergii. 

 E. orajaims. 



E. Jievadensis. 



E. unijlorus. 

 E. poliospemius. 



E. divergens. 

 E. ramosus. 



E. compositus discoideus. 

 E. Moomeri. 



E. erodiatus. 



E. canadensis. 



E. acris. 



E. acris debilis. 



