26 Plant-Breeding 



another, and they also err in supposing that a plant can 

 adapt itself to a cold climate only by developing a capa- 

 bility to withstand more cold. Indian corn is sometimes 

 cited as proof that plants do not become acclimatized, 

 for it is as tender to frost now as ever, for all that we know. 

 Yet this very plant affords a most unequivocal example of 

 complete acclimatization, because it has shortened its 

 period of growth fully one-half whereby it escapes the 

 cold of the North. 



The influence on plants of a change of climate, or, 

 what may amount to the same thing, the result of a trans- 

 fer of plants to new climates, is so complex and so general 

 that no discussion of the subject can be made at this 

 time. It will answer present purposes briefly to designate 

 the ways in which climate modifies plants : 



1. Climate generally modifies the stature of plants. 

 They become dwarfer in high latitudes and altitudes. 



2. It modifies form. Plants tend to be broader-headed, 

 and also more prostrate, in high latitudes and altitudes. 



3. Proportionate leafmess generally increases, at the 

 same time. 



4. There is also often a gain in comparative fruitful- 

 ness following transfer towards the poles. 



5. The colors of leaves, flowers, fruits, and seeds are 

 greatly influenced by climate, there being a general 

 tendency, in plants of temperate regions, to augmentation 

 in intensity of colors as they are carried towards the poles. 



6. There is modification in the flavor and essential 

 ingredients of various parts, following a change of climate. 



7. There is a variation in variability itself. The more 

 difficult the climate in which a plant finds itself, the more 



