5(')4 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Leaves hispiduloiis, (•ur\ed; rays 



pale yellow 5. E. curvi/uliu-s. 



Leaves c a n e s c e u t-p u b e r ii 1 e u t , 



straif^lit; rays bright yellow 10. t.jilijolius. 



Rays-iK)l }'ellow. 



Leaves cleft or parted. 



Leaves parted into narrow lobes 9. £". compositus. 



Leaves merely 3 to 5-cleft 9 a. E. composiius trijidus. 



Leaves entire or merely toothed. 



Stems branched, leafy, usually bear- 

 ing several heads. 



Pubescence long and diaise; 



rays blue, pink or white 4. E. hisjndis.mnus. 



Pubescence very short. 



Leaves linear-lanceolate, 3- 



nerved (J. E. con/mhosus. 



Leaves filiform or linear, I- 



nerved 11. E. Ihuunti 



Stems simple, scapiform; head al- 

 ways solitary. 



Leav(>s dentate, l)roadly spatu- 

 late. 



Involucre glandular; stems 



not producing ofl'sets. .. . 13. E . Icihc.rgii. 

 Involucre glabrate; stems 



producing rosulate ofl'sets. 15. E.arajmius. 

 Leaves entire: in\olucre not 

 glandular. 



Kays white, leaves linear- 

 lanceolate - - . 8 E. iicvadciisls. 



Rays violet. 



Involucre very woolly. 14. E. uidjlorus. 

 Involucre hispidulous . 7. E. polios-pennus. 

 Roots annual, liljrous; leaves toothed or lobed. 



Stems diil'usely Ijranched; rays pink 100 to 120. . . 17. E. diveiyens. 

 Stems erect, branched al)ove: rays white 40 to 60. . 18. E. rajnosus. 

 Rays very short or wanting. 



Plants low, root stout, perennial: heads solitary to 

 numerous. 



Leaves tcMiiately cleft or parted: involucre hirsute. 9b. E. comjiositusdiscoidcus. 

 Lea\('s linear or linear-spatulate, narrow: invo- 



hu'ri; villous 20. E. Uoumtri. 



Plants tali: heads .several to numerous. 



Rays wanting; heads cymose; leaves lirm: root pe- 

 rennial 19. E. cnidiatus. 



Rays present, short. 



Heads {janiculate: involucre glabrous; root an- 

 nual 21 . E. canadensis. 



Heads corymbose; involucre hirsute at least 

 at base; roots biennial. 



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



Low 10 to 20 cm. ; heads few 22 a. E. acris dehilis. 



