LESSONS WITH PLANTS 



335 



number of small flowers closely grouped together in a flat 

 head. On account of this structure the head is called a 

 composite flower. This grouping is a device to make more 

 of a show than if the little flowers were scattered separately 



FIG. 134. 



A section of a sunflower showing- involucre bracts, rayflowers, and small tubular flowers standing- 

 on the flat receptacle. The central flowers are still closed. Then come several showing stamens, 

 and the outer ones have gone to seed. 



over the plants. Thus insects are more apt to be drawn to 

 them. 



The above named composites have two sorts of flowers, 

 the ray flowers at the margin and a centre of tubular flowers. 

 But there are modifications of this type. Some composites, 

 like the dandelion and double aster, chrysanthemum, daisy, 

 and zinnia, have only strap-shaped flowers throughout the 



