COMPOSITAE 



alternate (except in Eupatorium). 

 P. Bracts of involucre distinctly in 2 sets; the 

 principal ones (inner) equal, essentially in 

 a single series; the outer (bractlets) very 

 much shorter, or sometimes obsolete. 



Lvs. palmately parted 



Lvs. pinnately parted 



PP. Bracts of involucre not in 2 sets, regularly 

 graduated in length, in 3 or more series. 

 Q. Lvs. opposite at least to middle of stem: 

 pappus of equal hair-like bristles only. . 

 QQ. Lvs. alternate: pappus not as above. 



Heads small; the involucre only about 

 4 mm. high: pappus double; the 

 inner of fine hair-like bristles; the 

 outer (inconspicuous) of very short 



bristles: receptacle naked 



Heads medium or rather large; the in- 

 volucre 1cm. high or more: pappus 

 of strongly graduated paleae: recep- 

 tacle densely bristly. 

 Involucral bracts (outer ones) with 

 dentate scarious white or purplish 

 margins and tips: outer corollas 

 of head enlarged and palmately 



lobed: lvs. mostly entire 



Involucral bracts entire, mucronate- 

 tipped, without conspicuous mar- 

 gin: outer corollas not enlarged: 



lvs. mostly pinnatifid 



FF. Strap-shaped ray fls. present. (In Centaurea (our species) the outer 



corollas are enlarged and falsely ligulate. Look for it in " F." 



In Gerbera the ray corollas are actually bilabiate but the 2 inner 



lobes are small and inconspicuous, and it is placed in " FF."). 



R. Rays white, red, blue, or violet, never yellow. 



S. Pappus of numerous slender hairs (sometimes with an outer 

 series of short more or less connate squamellae). 

 T. Disk corollas distinctly 2-lipped: plant scapose: achene 



beaked 



TT. Disk corollas regular, 5-toothed: plants not scapose: 

 achene not beaked. 



Outer bracts of involucre herbaceous throughout, 



linear or spatulate, much surpassing the inner. . 



Outer bracts of involucre not herbaceous (except 



sometimes at tip), shorter than the inner or at 



most not surpassing them. 



Rays (white) very short and inconspicuous, scarcely 



surpassing the involucre 



Rays (white or colored) conspicuous, much surpass- 

 ing the involucre. 

 Phyllaries 2-3-seriate, essentially equal, narrowly 

 lanceolate, acuminate, submembranous with- 

 out herbaceous tip: pappus of ray fls. of 

 small squamellae only (or rarely with a few 



33. Cacalia 

 32. Gynura 



3. Eupatorium 



1 . Vernonia 



44 . Centaurea 



43. Serratula 



U. 



UU. 



47. Gerbera 



6. Callistephus 



8. Erigeron 



390 



