8 THE EVOLUTION OF PLANTS 



nips, Wheat and Oats, with their numerous 

 varieties and races, all came originally from 

 wild species, often extremely different from the 

 garden or field plants which man has created out 

 of them. We will not go into the question how 

 the cultivated forms came from the wild types 

 that is a long and involved story, always 

 difficult and often impossible to unravel in de- 

 tail. For example, the origin of Wheat, the 

 most important to us of all cultivated plants, 

 has long been a mystery, and is not yet fully 

 cleared up. The Wheats have now been traced, 

 as Dr. Stapf informs us, to four primitive types. 

 The most important of the wild species (the 

 original of the Hard Wheats and other forms) 

 has only been recognised within the last few 

 years as a weed growing on the slopes of Mount 

 Hermon in Palestine; the wild form of the Soft 

 Wheats is still unknown. 



But, whatever the difficulties, we at any rate 

 know that all cultivated plants have come from 

 pre-existing wild forms by descent with modi- 

 fication. This, however, is Evolution, and we 

 arrive at the conclusion that all those plants of 

 which we know the origin have been evolved 

 from other, different plants which existed before 

 them. 



Cultivated forms are not of the same nature 

 as wild species, for the conditions under which 



