92 REPRESENTATIVE PLANTS 



(a) A square rod of waste ground had 20 large plants of 

 lettuce. 



(6) Each plant averaged 10,000 seeds. 



(c) The second year the plot had no more plants than it 

 had the year before. 



(d) Why was there such an enormous seed production ? 

 and 



(e) Why are there not more plants on the original plot? 



Note. The Composite is the largest family of plants, and, as a 

 rule, the most abundantly represented by species in any locality. The 

 individuals also are numerous. Now, as one half of Compositie fruits 

 are down-bearing, what influence would this have on the abundance 

 and general distribution ? (See study of Compositse flowers. ) 



Other fruits. 1. Study the vnnged fruits of ash, maple, 

 hop tree, or Ailanthus, and the winged seeds of pine, spruce, 

 catalpa, or birch. Observe the size, form, and adaptation of 

 each sort for dispersal by wind. Make drawings to illustrate 

 the results of your observations. 



2. Examine the dry fruits of the evening primrose, Jimson 

 weed, poppy, or others of similar nature. How are the 

 seeds distributed? In these fruits what do you discover 

 about the size of the seed ? Are the seeds few or many, 

 hard or soft? 



Conclusions. Write an essay on the dispersal of seeds, 

 based upon the results of your observations in the foregoing 

 studies. Make your statements clear and specific. 



