CULTIVATED PLANTS 



433 



selection of seed from plants taller than their neighbors, the 

 length of the fibers has been gradually but steadily increased. 



Wheat is a paying crop and is so much in demand for flour 

 and cereals that attempts have been made to grow it in many 

 different climates. But grains of wheat which will yield a 

 magnificent crop in warmer regions are killed by the rigors of the 

 northern winter. In order to obtain plants which will grow 

 in the cold regions of 

 northern Canada, for 

 example,it was neces- 

 sary to select seeds 

 from plants which 

 best endured cold 

 weather, and as a 

 result seedshavebeen 

 obtained which de- 

 velop into plants 

 capable of enduring 

 intense cold. 



By artificial polli- 

 nation and by selec- 

 tion of seeds, we are 

 constantly changing 

 the nature of the 

 plants around us, and 

 are replacing those 

 which are less desirable by those which are more desirable 

 (Fig. 300). 



Cultivated plants. In earliest times man secured his food 

 from wild crops, choosing from the multitude of plants those 

 which best suited his individual taste. Many of the wild plants^ 

 like the thistle, furnished nothing which he cared to eat; others, 

 like the wild cherry tree, furnished fruit which remained good 



FIG. 300. i, Wild gooseberry; 2, improved by 

 selection. (After Andrews.) 



