PHYSIOLOGICAL PROCESSES IN PLANTS 117 



a. Hydrophyte Society 



Observations. 1. Select any region where there is a pond, marsh, or 

 running water, and plenty of water plants. Find out the names of the 

 plants, if you can; if not, give any common names, or describe them as 

 best you can. Are there few or many plants ? 



FIG. 34. Photograph of plant societies, 

 vegetation. 



Note the different zones of 



2. Are there any plants entirely submerged? Any floating? Do 

 any rise in the air ? 



3. What differences between submerged leaves and those exposed to 

 the air ? 



4. How do the roots of plants entirely free from the soil differ from 

 ordinary roots? 



Conclusions. 1. Are submerged leaves affected by sun exposure ? If 

 not, do they need to be as entire and fleshy ? Explain. 



2. How must floating plants obtain their supply of soil substance ? 



3. What takes the place of leaves in the algalike plants ? 

 Observations. 1. Cut off the stems of some of the larger water plants, 



and note their interior structure. How would you describe it ? 



2. Look for stomata with a hand lens, or after returning from your 



