COMPOSITAE 



GG. Pappus present. 



I. Pappus of strongly plumose hairs or bristles (the lateral 

 hairs many times as long as the diameter of the main 

 hair). 

 J. Outer phyllaries pinnately dissected into linear 



spinescent divisions 38 . Atractylis 



JJ. Outer phyllaries not pinnately dissected. 



Lvs. with spiny teeth or lobes 42. Cirsium 



Lvs. not spiny. 



Heads not in racemes: stems If y. throughout 40. Saussurea 



Heads in racemes: lvs. crowded at middle or 



base of stem 46 . Ainsliaea 



II. Pappus not of strongly plumose hairs (if at all plumose, 

 then with the lateral hairs only a few times as long 

 as the diam. of the main hair, as in Helichrysum. 

 K. Lvs. with spiny teeth or lobes. 



Heads 1— fid. , densely crowded into solitary ter- 

 minal globose glomerules about 4-5 cm. thick: 



pappus of many short scales 37. Echinops 



Heads many-fid., not crowded into a glomerule: 



pappus of simple hairs 41 . Carduus 



KK. Lvs. not at all spiny. 



L. Involucre composed of dry, scarious, papery or 

 scaly bracts. 

 Heads large, 3-5 cm. in diam., not clustered; 

 the involucre 1.5-2 cm. high, of con- 

 spicuous yellow, reddish, purple, or white 

 bracts: plant green and essentially glab- 

 rous 11. Helichrysum 



Heads much smaller, less than 1 cm. in diam., 



crowded or clustered; the involucre less 



than 1cm. high: plant wooly. 



Involucre bright white; the bracts firm and 



almost papery: internodes narrowly 



winged throughout 9. Anaphalis 



Involucre yellowish to bright yellow; the 

 bracts thin and scarious: internodes 



winged only above if at all 10. Gnaphalium 



LL. Involucre not composed of dry scarious, papery, 



or scaly bracts. 

 M. Bracts of involucre stiffly hooked at apex .... 39. Arctium 

 MM. Bracts not hooked at apex. 



N. Involucre double; the outer of herbaceous 

 bracts; the inner of membranous bracts: 

 each fl. in the head subtended by a mem- 

 branous pale 25 . Bidens 



NN. Involucre otherwise: receptacle without pales 

 (but sometimes stiffly setose). 

 O. Pappus of 5 acuminate paleaceous awns: in- 

 volucral bracts 2-seriate, but essentially 



equal in length: lvs. opposite 2. Ageratum 



00. Pappus otherwise: principal bracts of involu- 

 cre either strongly graduated in length, or 

 else equal and essentially in a single series: 

 lvs. 



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