CHAPTER XXVII 

 CONTENTION WITH PHYSICAL ENVIRONMENT 



338. THE PHYSICAL ENVIRONMENT. We have seen 

 (326) that the environment in which a plant grows is 

 made up of two sets of factors the physical environ- 

 ment of climate and soil, and the organic environment 

 of competing animals and plants. 



339. ADAPTATION TO CLIMATE IN GENERAL. Every 

 particular climate causes particular modifications in its 

 plants. There are two general ways, however, in which 

 plants are modified or adapted to climate: modification 

 in the length of the period of growth; modification in 

 stature. Any modification of the plant, visible or invis- 

 ible, which adapts it to grow in a climate at first inju- 

 rious to it, is acclimatization. 



340. In short -season climates, plants hasten their 

 growth. They mature quickly. Indian corn may re- 

 quire five or six months in which to mature in warm 

 countries, but only three months in very cold countries. 

 Nearly all garden vegeta- 

 bles mature quicker from 



the time of planting in the 

 North than in the South 

 when they are raised from 



Seeds grOWU in their respec- 350. Germination of corn grown in 



tive localities. Seedsmen are New York (on the left) and in Alabama ' 

 aware of this and they like to raise seeds of early varieties 

 in the North, for such seeds usually give "early" plants. 

 Many plants which are perennials in warm countries be- 

 come annuals or plur- annuals in cold countries (14). 



(203) 



