56 HANDBOOK OF NATURE STUDY 



common spring-scale a large, full-grown sunflower plant, 

 with roots, leaves and all. How many times is the weight 

 of the seed contained in the weight of the mature plant? 

 In how long a time does this wonderful growth take place ? 

 If your plant is three months old, how much was its average 

 gain in weight per day ? Where did this rapidly increasing 

 material come from ? Will a plant grow if you cut off all 

 its leaves ? Make the experiment. 



29. The Composite Family. 



MATERIAL : Sunflowers, goldenrods, asters, blazing star, and other 

 composites of the season brought by the children. 



Here we have many flowers of the season, some very showy 

 and a few quite modest in appearance. In my left hand I 

 hold ten flowers, differing much in size and color ; but all 

 agree in one thing. Their larger heads consist of many tube 

 or strap-shaped florets, growing from a common receptacle and 

 surrounded by a common involucre. TJiey all belong to the 

 Composite family, of which we studied the Sunflower as the 

 type. 



Here are some thistles and blazing stars. Examine their 

 florets and you will find them all tubular. Here is a dande- 

 lion, which has all the florets strap-shaped. Other flowers 

 resemble the sunflower very closely. They have a margin 

 of large, showy rays ; but the inner florets are tubular. Can 

 you tell to which one of these three divisions each one of 

 our composites belongs ? 



Muller, in his famous book on "The Fertilization of 

 Flowers," mentions the following points, which combined 

 so well to fit the composites to survive in the struggle for 

 existence : 



1. The close association of many florets. This makes 

 them more conspicuous and attracts more insects. Insects 

 can fertilize numerous florets in a very short time. The 



