/ii.] INFLORESCENCE. S<; 



inflorescence forms a compound iimhel ; the umbels of single 

 flowers being tho. partial umbels. 



Observe the ring of small leaves at the base of the 

 pedicels in the Carrot, forming an involucre. In compound 



Fig. 57. Vertical section through a flower-head of Zinnia. The receptacle convex. 



umbels we frequently have both general and partial in- 

 volucres; the former surrounding the compound umbel, 

 the latter each partial umbel. 



Fig. 58. Section of flower-head of Sonchus. The receptacle plane. 



Suppose, now, all the flowers of a simple umbel to be 

 sessile. We should have the same form of inflorescence 

 as we find in Zinnia and Sonchus, in which a numbei 



