KEY. 275 



Flowers not all, or none of them perfect. (Heads 

 heterogamou's, or dioecious) 926 



019. Involucral scales imbricated 922 



Involucral scales in one row (or nearly so) 920 



930. Leaves ample. Heads rather large, whitish, or yel- 

 low-flowered 921 



Leaves linear. Heads very small 953 



931. Flojvers whitish, or cream-color. Heads 5- to many- 

 flowered, rather large, in flat corymbs. Cacalia. 



Flowers yellow. Heads many-flowered, solitary, or 

 corymbed. Leaves pinnatifid and toothed, clasping. 



Senecio vulgaris, L. (958). 



933. Flowers whitish, or purple 923 



Flowers yellow. Achenia inversely conical. Re- 

 ceptacle with an awl-shaped prolongation in the centre. 

 Leaves oblanceolate, or linear, 1- to 3-nerved. Heads small, 

 in a flat-topped corymb. Bigelovia nudata, D. C. 



933. Flowers whitish 925 



Flowers purple 924 



934. Pappus double ; the outer a row of very short, the 

 inner of longer bristles. Heads of. purple flowers, in fastigi- 

 ate cymes. Involucral scales sometimes tipped with an awl- 

 shaped appendage. Vernonia. 



Pappus simple. Bristles of the pappus plumose, or 

 at least conspicuously bearded, stiff. Achenia slender, ta- 

 pering to the base, about 10-ribbed. Leaves entire. Heads 

 spicate-racemose, or panicled-cymose. Liatris. 



93o. Pappus capillary. Achenia 4-cornered. Herb 

 much branched. Leaves pinnately dissected. Heads in a 

 pyramidal panicle, small, 3- to 5-flowered. Stem 3 to 10 feet 

 high. Eupatorium fceniculaceum, Willd. 



{Dog-fennel.) 



Pappus very plumose. Achenia terete, many-stri- 

 ate. Leaves chiefly toothed and lanceolate ; upper ones li- 

 near and entire. Heads panicled-corymbose. 



Kuhnia eupatorioides, L. 



