VASCULAR PLANTS. 31 



33. Madia, Molina. 



Superflua. Necessaria. iEqualis. Ray-flow- 

 ers ligulate, 3-dentate, scarcely longer than the 

 involucre. Involucre 1-seriate, herbaceous ; 

 scales carinate, complicate, embracing the ray 

 akenes. Receptacle naked in the centre, with 

 1 — 2 rows of paleaa between the disk and ray. 

 Akenes laterally compressed ; pappus in the 

 ray ; in the disk usually 0. 



. 21- viscid, resinous, flowers yellow. 



34. Hemizonia, DC. 



Necessaria. Superflua. Ray-flowers ligulate, 

 dentate, scarcely longer than the involucre. 

 Involucre 1-seriate, with concave scales embra- 

 cing the ray-akenes. Receptacle flat, naked 

 in the centre, with a row of paleae between disk 

 and ray or sometimes throughout. Akenes of 

 the ray convex externally, flat internally ; pap- 

 pus 0, or plumose in the ray ; scaly, aristate, 

 plumose or in the disk. 



0. viscid/resinous, flowers yellow, white. 



35. Holozonia, Greene. 



Necessaria. Superflua. Disk -flowers go; 

 ray-flowers 5 — 8, cuneiforn, 3-cleft. Scales of 

 the involucre corresponding in number to the 

 ray-flowers, and completely embracing each 

 akene. Receptacle flat, the paleae united into 



