28o 



PLANT FAMILIES: DICOTYLEDONS. 



The floral formula for the composite family then is as follows : 

 Cas, C05, A5, G2. 



Fig. 240. Fig. 241. 



Ray flower of Aster Tubular flower 

 novae-angliie. of aster. 



Fig. 242. 

 Tubular flower 

 opened to show syn- 

 genecious stamens. 



Fig. 243. 

 Sy ngenec ious 

 stamens opened to 

 show style and two 

 stigmas. 



442. Other composites. — The rattlesnake-weed (Hieracium 

 venosum) is an example of another type, with only one kind 

 of flower in the head, the true ligulate flower. The hawk- 

 weed, or devil's paint-brush (H. aurantia- 

 cum) is a related species, which is a 

 troublesome weed. The dandelion and 

 prickly lettuce are also members of the 

 ligulate-flowered composites. A number of 

 the composites have only tubular flowers, as 

 in the thoroughwort (eupatorium) and ever- 

 lasting (antennaria). 



443. The composites are the most highly developed plants. 

 — The extent to which the union of the parts of the flower has 

 been carried in the composites, and the close aggregation of 

 the flowers in a head, represent the highest stage of evolution 

 reached by the flowers of the angiosperms. 



Fig. 244. 

 Diagram of composite 

 flower. (Vines.) 



