COMPOSITE FiKMILY COMPOSITAE 



KEY TO GENERA 



1. All corollas strap shaped 2 



All corollas tubular 9 



Both strap-shaped and tubular corollas present 17 



2. All or nearly all leaves basal 3 



Some of the leaves on upright stems 4 



3. Pappus composed of scales and bristles Krigia p. 386 



Pappus composed entirely of bristles Taraxacum p. 387 



4. Pappus of scales; flowers mostly blue Cichorium p. 385 



Pappus of bristles 5 



5. Pappus white 6 



Pappus creamy or yellowish 8 



6. Pappus like a feather Tragopogon p. 385 



Pappus hairlike 7 



7. Fifty or more flowers in each head Sonchus p. 388 



Not more than 30 flowers in each head Lactuca p, 389 



8. Flowers yellow Hieracium p. 392 



Flowers whitish or purplish Prenanthes p. 391 



9. Leaves and involucres very prickly Cirsium p. 383 



Leaves not prickly 10 



10. Involucres forming burs in fruit Arctium p. 382 



Involucres not forming burs 11 



1 1 . Plants woolly 12 



Plants not woolly 13 



12. Plants strongly odored Gnaphalium p. 357 



Plants not strongly odored Antennaria p. 356 



13. Pappus of bristles I4 



Pappus lacking; heads very small Artemisia p. 379 



14. Involucre composed of 5 bracts Cacalia p. 380 



Involucre of more than 5 bracts 15 



15. Leaves opposite or whorled Eupatorium p. 337 



Leaves alternate 16 



16. Heads arranged in a spike Liatris p. 343 



Heads not in a spike Vernonia p. 336 



17. Upper part of plant sticky or gumlike Grindelia p. 345 



Plant not sticky or gumlike 18 



18. Plants strongly odored 19 



Plants not strongly odored 21 



19. Leaves finely divided 20 



Leaves not finely divided Polymnia p. 358 



20. Disk flowers yellow Anthemis p. 377 



Disk flowers white Achillea p. 376 



21. Pappus composed ot bristles 22 



Pappus not composed ot bristles 26 



334 



