CHAPTER XXVII 



CONTENTION WITH PHYSICAL ENVIRONMENT 



388. THE PHYSICAL ENVIRONMENT. — We have seen 

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

 made up of two sets of faetors — the physical environ- 

 ment of climate and soil, and the orgriDir mrironment 

 of competing aninials and plant.s. 



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 groivth; 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 -sedsoit cliitiafes, 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 AM^>C^^^^^^S \.>....h\'.i,J.< 

 till' time of planting in the ^i 

 North than in the South I 

 when they are raised from =^*'**'* 

 seeds grown in their respec- "" (.uiMi.ntKMi ..i ,,.rn « """ m 

 tive localities. Seedsmen are ^""'"^^ ^"'^ ^"" '^'^ '^''^ ■'"'^ '" -''''^=''"*- 

 aware of this and they like to i-aise 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). 



1203) 



