14 General Botany 



swamps, bogs, cliffs, bottom lands, sand plains, and clay slopes 

 are examples. 



Every habitat affords a particular complex of environmental 

 factors. In a particular habitat we shall find only those plants 

 growing whose requirements are satisfied by the factors of that 

 habitat. In similar habitats, therefore, we expect the same or 

 similar plants ; in different habitats, different kinds of plants 

 having different requirements. Plants whose requisites are 

 very definite may occur only in a single habitat, while those 

 whose requirements are rather indefinite may live in a variety 

 of habitats. 



Summary. It is quite impossible to understand the life of a 

 plant without having constantly in mind the environment in 

 which the plant lives. The environment is made up of several, 

 or many, factors, among which are light, temperature, water, 

 gravity, and the various properties of the air and soil. Every 

 individual plant is modified in its development by these external 

 conditions. Plants growing wild, or as crops, are limited in their 

 development by the least favorable factors of the habitat. These 

 are called limiting factors. In nature, plants are not distributed 

 haphazard, but each occurs only in those habitats that afford 

 the conditions which are necessary for its development. Similar 

 habitats have the same or similar plants living in them. Habi- 

 tats that differ in character are occupied by dissimilar plants. 



