900 COMPOSITAE 



C. Pappus composed of bristles. 



Pappus double, the outer bristles very short, the inner ones longer. 



8751. Vernonia, p. 904. 



Pappus-bristles all of the same length, not in 2 series. 

 Heads aggregated into dense clusters. 



Foliage not spiny; heads few-flowered 



8775. Elephantopus, p. 905. 



Foliage spiny; heads 1-flowered 9442. Echinops, p. 998. 



Heads not aggregated into clusters. 

 Leaves prickly. 



Receptacle densely bristly. 



Pappus-bristles not plumose 9461. Carduus, p. 999. 



Pappus-bristles plumose 9462. Cirsium, p. 999. 



Receptacle not bristly 9467. Onopordum, p. 1003. 



Leaves not prickly. 



Pappus-bristles plumose or conspicuously upwardly barbed. 



Corollas whitish; heads corymbose 8825. Kuhnia, p. 910. 



Corollas rose colored, purple, or white; heads racemose or 



spicate 8826. Liatris, p. 911. 



Pappus-bristles not plumose or with inconspicuous barbs. 



Stems twining; leaves opposite, triangular-hastate; flowers 



flesh to pale purplish 8818. Mikania, p. 910. 



Stems not twining. 



Involucral bracts scarious throughout; plants more or less 

 white-woolly. 

 Plants dioecious; pistillate heads with a few perfect flowers 



in the center; perennial 8983. Anaphalis, p. 953. 



Plants not dioecious; all of the flowers fertile, the central 

 ones perfect, surrounded by pistillate ones; annual or 



perennial 8992. Gnaphalium, p. 954. 



Involucral bracts not scarious throughout or if so, the plants 

 not white-woolly. 



Involucral bracts hooked 9452. Arctium, p. 998. 



Involucral bracts not hooked. 

 Bracts of involucre in 1 series. 



Length of bracts about 15 mm 



9389. Erechtites, p. 994. 



Length of bracts about 10 mm or less. 



Cauline leaves pinnatifid 9411. Senecio, p. 996. 



Cauline leaves not pinnatifid. . 9409. Cacalia, p. 994. 

 Bracts of involucre in more than 1 series. 



Central disk flowers sterile ; anthers tailed at the base ; 



bruised foliage malodorous 



8941. Pluchea, p. 949. 



Central disk flowers fertile; anthers not tailed at the 

 base; bruised foliage not malodorous. 

 Leaves large, triangular, the lower ones hastate at 



the base 9409. Cacalia, p. 994. 



Leaves not as above. 



Leaves opposite or whorled; plants usually with 

 resinous dots; stigmatic lines only at the base 

 of the minutely and uniformly pubescent style 



branches 8816. Eupatorium, p. 905. 



Leaves alternate; plants not resinous; stigmatic 

 lines extending to the tips of the style 

 branches or their appendages. 



