SEED-BEARING PLANTS 



483 



believed to be derived. The method of pollination in 

 normal flowers is illustrated in Fig.. 3 70. 



424. Composite Family (Compositae). — The composites 

 represent the highest development of dicotyledons. The 

 flowers are borne on a common receptacle in a compact 



Fig. 367. — Sections of -flowers of the toad-flax [Linaria vulgaris)- 

 A, front view; a, anthers; s, stigma; ■«, nectar-gland. B, side view; o, 

 ovary. 



"head," giving the appearance, not so much of an in- 

 florescence as of a compound flower, whence the family 

 name, assigned by early botanists, who did not understand 

 the morphology of the head. 



■ The heads are surrounded by a circle of bracts, called 

 an involucre. The bracts which often occur on the re- 



