186 



PLANT RELATIONS. 



cat -tails. This regular arrangement in zones is so often 

 interfered with, however, that it is not always evident. 



The reed-swamp societies have been called " the pioneers 

 of land vegetation," for the detritus collects about them, 



i \ $ 



H 



Fig. It33. A reed swamp, fringing the low shore of a lake or a sluggish stream. The 

 plants are tall and wand-like, and all are monocotyls. Three types are prominent, 

 the reed grasses (the tallest), the cat-tails (at the right), and the bulrushes (a group 

 standing out in deeper water near the middle of the fringing growth). The plant 

 in the foreground at the extreme right is the arrow-leaf {Sagittaria), recognized 

 by its characteristic leaves.— After Keener. 



the water becomes more and more shallow, until finally 

 the reed plants are compelled to migrate into deeper water 

 (see §108). In this way small lakes and ponds may be 

 completely reclaimed, and become converted first into 

 ordinary swamps, and finally into wet meadows. Instances 



