ASTERACEAE: ASTEREAE 175 
Glabrous or nearly so; involucral bracts awl-pointed. 
5. A. sagittifolius. 
Pale with fine gray pubescence; bracts acute. 
4. A. drummondii. 
Leaves, if cordate, sessile or nearly so, some of them often cordate- 
clasping. 
Stems hirsute or hispid-pubescent. 
Leaves entire. 
Rays 40-50, 10-15 mm. long. 6. A. novae-angliae. 
Rays 20-30, 6-10 mm. long. 7. A. oblongifolius. 
Leaves sharply serrate. 8. A. puniceus. 
Stems glabrous or slightly pubescent in streaks. 
Leaves densely silvery-white pubescent on both sides. 
13. A. sericeus. 
Leaves not silvery pubescent. ‘ 
Rays blue, violet or purple, rarely white. 
Stem leaves, at least the upper, cordate clasping, lanceolate 
or oblanceolate. 
Outer bracts of the involucre shorter than the inner, not 
foliaceous. 9. A. laevis. 
Outer bracts of the involucre as long as or longer than the 
inner, foliaceous. 12. A. foliaceus. 
Stem leaves, if clasping, linear or linear-lanceolate. 
Rays purple, about 12 mm. long. 15. A. nebraskensis. 
Rays white, violet or purplish, 6-10 mm. long. 
Leaves narrowly linear. 
Leaves with ciliate margins. 14. A. fendleri. 
Leaf-margins not ciliate. 18. A. longulus. 
Leaves linear-lanceolate to oblanceolate. 
Heads few, leaves entire or nearly so. 
Involucral bracts in 3-5 series. 10. A. adscendens. 
Involucral bracts in 1-2 series. 11. A. longifolius. 
Heads numerous, leaves usually serrate. 
Disk 1 cm. wide; rays rarely white. 
16. A. salicifolius. 
Disk 6-8 mm. wide; rays generally white. 
17. A. paniculatus. 
Rays white, 3-8 mm. long. (See also A. laevis and A. longulus). 
Heads 10-25 mm. broad. 
Leaves acute or acuminate, often serrate. 
Rays 6-8 mm. long; leaves with rough margins. 
Disk 1 cm. wide, leaves thickish. 16. A. salicifolius. 
Disk 6-8 mm. wide; leaves thin. 
Leaves lanceolate. 17. A. paniculatus. 
Leaves linear. 17a. A. paniculatus var. bellidiflorus. 
Rays 4-6 mm. long. 19. A. tradescanti. 
Leaves obtuse, entire. 23. A. commutatus. 
Heads 6-8 mm. broad, rays 3-4 mm. long. 
Bracts, especially the inner, acutish. 
Leaves nearly glabrous. 20. A. multiflorus. 
Leaves pubescent and ciliate. 21. A. exiguus. 
Bracts very obtuse. 22. A. polycephalus. 
