KEY. 273 



E. COMPOSITES. 



904. (3.) Tuhuliflorm. Heads presenting tubular flow- 

 ers — alone or with ligulate ones 905 



LiguliflorcB. Heads with all the flowers ligulate. 

 Plants with milky juice 987 



90^. Heads discoid — that is, without ligulate flowers 



(rays), at least apparently so 906 



Heads radiate — that is, with the outer flowers ligu- 

 late (rays) 943 



906. I. Receptacle (at least in the centre) naked — that 

 is, with no pales or bristles among the flowers; very rarely 

 hairy 907 



n. Receptacle chafly, having pales or little scales 

 among the flowers 931 



in. Receptacle bearing bristles, or deeply honey- 

 combed 938 



907. Pappus of scales, or bristles present 912 



Pappus none, or a short-toothed margin 908 



908. Heads alike. Leaves alternate 909 



Heads of two sorts on the same plant, the sterile 



top-shaped, and 5- to 20-flowered, the fertile 1-flowered. 

 Leaves lobed or dissected, opposite or alternate. 



Ambrosia. 



909. Heads beset with glands, whitish, loosely panicled. 

 Leaves triangular, or somewhat heart-shaped, white-woolly 

 beneath ; petioles margined. Stem leafless above. Achenia 

 long, club-shaped, glandular. 



Adenocaulon bicolor, Hook. 



Heads glandless. Leaves, at least the lowei ones, 



more or less pinnately incised or (once- to thrice-) dissected. 



Heads yellowish-white, yellow, or purplish 910 



910. Receptacle conical or convex. Corollas yellow. 

 Pappus a short, o-lobed or toothed crown 911 



Receptacle flattish. Flowers mostly of 2 sorts, the 



central ones usually sterile. Corollas yellow or purplish. 



Racemes or panicled spikes. Plants often hoary or whit- 



ened-wooUy. Artemisia. 



