CHAPTER XXIX 



CONTENTION WITH PHYSICAL ENVIRONMENT 



366. The Physical Environment. — We have seen (354) 

 that the environment in which a plant grows is made up 

 of two sets of factors — the physical environment of climate 

 and soil, and the organic environment of competing animals 

 and plants. 



367. Modifications to Climate in General. — Every par- 

 ticular climate induces particular modifications in its plants. 

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

 modified by climate: modification in the length of the 

 period of growth; modification in stature. Any modification 

 of the plant, visible or invisible, that enables it to grow in a 

 climate at first injurious to it, is acclimatization. 



368. In short-season climates, plants hasten their growth. 

 They mature quickly. Indian corn may require five or six 

 months in which to mature in warm countries, but only 



three months in very cold 

 countries. Garden vegetables 

 probably mature quicker 

 from the time of planting in 

 the North than in the South 

 378. Germination of corn grown in when they are raised from 



New York (on the left) and in Alabama. -, ,1 • „ 



seeds grown m their respec- 

 tive localities. Some seedsmen think this to be true and 

 they like to raise seeds of early varieties in the North, for 

 such seeds usually give "early" plants. Many plants that 

 are perennials in warm countries become annuals or plur- 

 annuals in cold countries (14). 



369. Plants are usually dwarf or smaller in stature in 



(212) 



