224 



PLANT SOCIETIES 



. An aquatic society in which several 

 kinds of plants grow side by side, 



keeps his wild pastures 

 "clean" by turning in 

 sheep : the sheep are fond 

 of browsing. 



365. Some plants as- 

 sociate. They grow to- 

 gether. This is possible 

 largely because they di- 

 verge or differ in character 

 (352). Plants associate in 

 two ways: by growing side 

 by side; by growing above 

 or beneath. In sparsely populated societies (as in Fig. 

 377) plants may grow along- side each other. In most 

 cases, however, there is overgrowth and undergrowth : 

 one kind grows beneath another. Plants which have 



become adapted to shade 

 (354) are usually under- 

 growths. In a cat - tail 

 swamp (Fig. 378), grasses 

 and other narrow - leaved 

 plants grow in the bottom, 

 but they are usually unseen 

 by the casual observer. 

 Search the surface of the 

 ground in any swale or in a 

 meadow. Note the under- 

 growth in woods or under 

 trees (Fig. 379). Observe 

 that in pine and spruce 

 forests there is almost no 

 undergrowth, because there 

 is very little light. Fig. 3G2. 

 366. On the same area 



ais. virasses and narrow-leaved plants 



grow between the cat-tail flags. the societies may differ at 



