PLANT BREEDING 



317 



varieties thus produced have been selected and bred from, 

 as described in Sects. 392, 394. 



396. How Hybrids are Artificially Produced. — Hybridiz- 

 ing, or crossing, plants is sometimes an easy, sometimes a 

 rather difficult, process. It is simplest in unisexual flowers, 

 for example, in those of Indian corn. Here the " tassel " 

 is a cluster of spikes of staminate flowers and tfee " ear " 

 is a spike of pistillate flowers, each thread of the " silk " 

 representing a stigma and style attached to an ovary (grain 



Fig. 222. A Peach Flower prepared 

 for Hybridization. 



A, flower cut round for removal of the 

 stamens ; B, longitudinal section of a 

 flower showing level «, at which the 

 cross-section was made iu A. 



of corn). In hybridizing corn it is only necessary to tie 

 a paper bag over the ear before the silk appears, in order 

 to keep off stray pollen, leave it covered until full grown, 

 then remove the bag, dust the silk thoroughly with pollen 

 from tassels of another variety of corn, and keep the ear 

 covered until the silk is entirely withered. 



In most cases of hybridizing it is necessary to go through 

 with about the following process : 



(1) Select the flower to be pollinated, before it opens 

 or its own pollen is mature. If it is one of a cluster of 



