1404 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM 



Corollas with short tube and scarcely distinct throat. 



9. AQERATUM. 

 Corollas with slender tube, abruptly widened into the throat. 



10. OXYLOBUS. 

 Tribe III. Astereae. 

 Plants dioecious or polygamo-dioecious. 



Plants dioecious, the heads strictly staminate or pistillate. 



29. BACCHARIS. 

 Plants polygamo-dioecious, the staminate heads as in Bnccharis, the pistillate 

 with 1 to 15 central hermaphrodite flowers. 



30. ARCHIBACCHARIS. 

 Plants not dioecious or polygamo-dioecious. 

 Pappus of squamellae or awns, or wanting. 



Pappus wanting 22. SELLO A. 



Pappus present. 



Pappus of about 10 oblong to lanceolate squamellae; flowers yellow. 



23. GUTIERREZIA. 

 Pappus of about 15 to 30 squamellae or awns; flowers white, changing to 



rose-purple 26. GREENELLA. 



Pappus of bristles, sometimes with an outer series of short squamellae. 

 Flowers all yellow, the rays or disk rarely turning purple in age. 



Phyllaries in distinct vertical ranks; heads (in our species) discoid, 



5-flowered 25. CHRYSOTHAMNUS. 



Phyllaries not in distinct vertical ranks; heads often radiate, usually 

 with more than 5 flowers. 

 Plants not glaucescent, usually resinous or pubescent. 



24. APLOPAPPUS. 



Plants glaucescent, glabrous, not resinous. Leaves linear, mostly 



1 cm. long or less; phyllaries cuspidate-acute or acuminate {A. 



car7iosus) 27. ASTER, 



Flowers (at least those of the ray) white to violet. 



Involucre distinctly graduate; style tips acute or acuminate. _ 27. ASTER. 

 Involucre obscurely or not at all graduate; style tips short, obtuse. 



28. ERIGERON. 

 Tribe IV. Inuleae. 

 Flowers all hermaphrodite, the corollas tubular; pappus stiff, of about 10 bar- 

 bellate bristles and about 30 shorter, somewhat connate bristles. 



34. PELUCHA. 

 Outer flowers (3 to many) pistillate, with filiform corollas, the inner (1 to many) 

 hermaphrodite, with tubular corollas; pappus 1-seriate, of essentially equal 

 bristles. 

 Heads few (about 4)-flowered, the hermaphrodite flowers solitary. 



32. ACHYROCLINE. 

 Heads many-flowered, the hermaphrodite flowers several or numerous. 



Phyllaries dry, but not scarious 31. PLUCHEA. 



Phyllaries scarious 33. GNAPHALIUM. 



Tribe V. Heliantheae. 

 Plants monoecious. Pistillate involucre gamophyllous, 1 to 8-flowered, the 

 staminate many-flowered. 

 Pistillate involucres bearing transverse scarious wings. ,43. HYMENOCLEA. 

 Pistillate involucres spiny 44. FRANSERIA. 



