34 



ASTERACEAE 



(b) Heads in flat-topped clusters, or single 

 x. Involucral scales dry and papery, yellow to white or red 

 (x) Leaves white-cottony, extending along the stem as wings 

 (y) Leaves not white-cottony, stem not winged 

 y. Involucral scales not papery, usually green 

 (x) Heads white, yellowish or purplish ; native 

 m. Heads white, pink or purplish 

 n. Heads yellowish 

 (y) Heads deep purple or blue 

 m. Heads deep purple ; native 

 n. Heads blue, rarely white; cultivated 

 b. Flowers greenish ; heads inconspicuous 



(1) Leaves broad, ovate, not deeply lobed 



(a) Involucre forming a hooked bur 



(b) Involucre not hooked 



(2) Leaves narrow or deeply lobed 

 (a) Leaves strong-scented 



x. Pappus a short crown 



Ammobium 

 Heliclirysum 



Eupatoriurn 

 Kuhnia 



Vernonia 

 Ageratum 



Xant hium 

 Iva 



Tanacelum 



Radiate head of Cosmos with long section, ray flower and tubular or disk flower. 



