AQUATIC VEGETATION 



239 



lucens (shining pondweed), entirely submerged ; yellow 

 water-lily, mare's- tail, Pilularia, Myriophyllum, and 

 Char a. 



The water of pools which occur on peaty soil contains 

 a large amount of soluble organic matter, and the vegeta- 



FIG. 110. Isoetes lacustris (QUILLWORT). 



tion is characteristic. The most frequent plants are the 

 bladderwor/fcs, Potamogeton natans, Scirpus fluitans (float- 

 ing club-rush), Myriophyllum spicatum, and water- violet. 



