Spring Flora of Oklahoma 
187 
Receptacle naked. 
Receptacle convex. 
Pappus of capillary bristles, leaves bristly-serrate. 
I. Sideranthus. 
Pappus of scales. 
Bracts of the involucre appressed. 
XXII. Tetraneuris. 
Bracts of the involucre spreading or reflexed at 
maturity. XXIII. Helenium. 
Receptacle flat or nearly so. XXVI. Senecio. 
Rays white, pink or purplish. 
Rays many. 
Pappus present. 
Pappus of a dentate crown, or short teeth. 
Receptacle naked; achenes prismatic. 
II. Aphanostephus. 
Receptacle chaffy; achenes 4-sided. 
XVII. Echinacea. 
Pappus at least in part of awns or bristles. 
Pappus of a few long awns or coarse bristles, 
or in ray-flowers reduced to palea. 
IV. Townsendia. 
Pappus of numerous, capillary bristles, at least 
on the disk achenes. 
Involucre turbinate; bracts imbricated in sev¬ 
eral rows; rays white. VI. Leucelene. 
Involucres hemispheric or broad; bracts in 1-3 
rows; rays white to purple. VII. Erigeron. 
Pappus none, or a ring of minute bristles. 
III. Beilis. 
