//. Key to Genera of Eupatorieae 



1. Achenes with 10 to 20 (rarely 6 to 9) ribs; phyllaries indefinite in number 



2. Liatris, p. 1595 



1. Achenes normally with 5 (rarely 4 or 6) ribs or angles, prismatic or sub- 



prismatic, rarely compressed; phyllaries definite or indefinite in 

 number (2) 



2(1). Pappus a low irregular crown of connate scales 0.3 mm. long or less, or 

 essentially absent 3. Trichocoronis, p. 1599 



2. Pappus much longer than 0.3 mm., usually of awns or bristles (3) 



3(2). Phyllaries uniformly 4 per head 4. Mikania, p. 1599 



3. Phyllaries more than 4 per head 5. Eupatorium, p. 1601 



///. Key to Genera of Aster eae 



1. Heads unisexual; male and female heads on separate plants 



6. Baccharis, p. 1606 



1. Flowers (at least disk flowers) perfect (2) 



2(1). Rays white, pink, violet or purplish, never yellow (3) 



2. Rays yellow, sometimes pale-yellow, or absent (16) 



3(2). Pappus of disk flowers absent or reduced to a mere vestige or paleaceous 

 crown less than 0.5 mm. long (4) 



3. Disk flowers with a manifest nonvestigial pappus (5) 



4(3). Phyllaries 0.8-1.6 mm. broad; upper herbage densely viscid-pubescent with 

 glandular-capitate hairs 16. Egletes, p. 1631 



4. Phyllaries 0.4-1.1 mm. broad; upper herbage pubescence not viscid nor 



glandular 13. Erigeron, p. 1626 



5(3). Receptacle conical or hemispherical to beehive-shaped (6) 



5. Receptacle flat to slightly convex (7) 



6(5). Achenes with true ribs extending from base to summit, not winged 



13. Erigeron. p. 1626 



6. Achenes lacking true ribs but winged 15. Boltonia, p. 1630 



7(5). Pappus of disk flowers at least partly of scalelike members, if bristlelike 

 then these not capillary but relatively coarse and basally dorsiven- 

 trally flattened 13. Erigeron, p. 1626 



7. Pappus of disk flowers of numerous capillary bristles (8) 



8(7). Pappus bristles manifestly in 2 series (9) 



8. Pappus bristles in a single series or nearly so (10) 



9(8). Achenes with 2 definite ribs 13. Erigeron, p. 1626 



9. Achenes either unribbed or with several very weak ribs 



12. Doellingeria, p. 1626 



10(8). Phyllaries in 1 or 2 series (11) 



10. Phyllaries in 3 to many series (12) 



11(10). Tubular portion of ray corolla shorter than the remainder 



13. Erigeron, p. 1626 



11. Tubular portion of ray corolla longer than the remainder 



14. Conyza, p. 1630 



12(10). Pappus of ray flowers absent 9. Machaeranthera, p. 1609 



12. Pappus present in ray flowers (13) 



13(12). Base of plant distinctly woody 9. Machaeranthera, p. 1609 



13. Base of plant not woody ( 14) 



1589 



