THE STAGE SETT1\(; 



.l/M/irs 



Cypress trees have become adapted to live in swampy lands by developing 

 buttressed bases of the trunks and erect growths (knees) from the roots. Tliese 

 enable the tree to get sufficient air. 



Substratum 



Anything in which a plant grows or on which an animal comes to 

 rest is known as substratum. Types of soil differ from cold, dense, 

 clayey soils, which though they hold water do not readily give it up 

 to humus that is well aerated, has a high nitrogen content, hokls 

 water, and gives it up readily. The distribution of plants depends 

 to a considerable extent on the kind of soil found in a given locality. 

 For example, mosses and ferns grow in moist soil, while cacti are 

 found in sandy desert soils. Varying soil temperatures are brought 

 about by the kind of soil, whether coarse or fine ; by the pre.'^ence 

 of a blanket of living things over it ; by its color (dark soils absorb 

 heat more readily than light-colored soils) ; and by the water it will 

 hold (wet soils are cooler than dry). Great variations occur in the 

 air content of soils and this again determines the plants and animals 

 found in a given area. Water-soaked soil, for examj^le, contains 

 practically no air and does not ordinarily have a large jjiant or 

 animal population. In some cases a plant adapts itself to water- 

 soaked soil, as seen in th(> bald cypress. 



