CHAPTER X 



Origination of Varieties 



.,tt^r *^^gj^j? occasionally is found a new 

 variety which probably originated as a sport 

 from another variety (see under Result of 

 Cross-Fertilization in this chapter), in which the 

 special character distinguishing it from the parent 

 plant had become fixed (not dependent on environ- 

 ment). Generally, however, new varieties are obtained 

 only by cross-pollination. 



CROSS-POLLINATION is the conveyance of pollen 

 from an anther of one plant to a stigma of another, 

 but usually plants of different varieties or species are 

 intended. It is usually practiced not so much for the 

 purpose or with the expectation of obtaining a new 

 character at least not immediately as to obtain an 

 augmentation or a desirable combination of characters 

 possessed by the plants used in the operation. 



VARIETIES FOR CROSSING. Varieties differ greatly 

 as regards fertility. Some usually have either no 

 pollen or only sterile pollen, and some having fertile 

 pollen do not usually produce seed. The germanicse 

 and the intermediates, for instance, are much less 

 likely than many others to form seed at least in 

 many and probably most localities even when care- 

 fully pollinated. 



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