428 



PRACTICAL BOTANY 



with a camel' s-hair brush or other implement. It is safer to 

 take pollen from a flower that has been kept covered with a 

 paper bag to keep off foreign pollen. 



(4) Cover the pollinated flower again with a paper bag 

 until the fruit has grown considerably. 



392. General results of 

 hybridizing. As was men- 

 tioned before (Sect. 390), 

 hybrids are likely to be 

 extremely variable. Not 

 only may they differ from 

 either parent, but they may 

 also be unlike each other. 

 The differences include 

 such features as the form, 

 size, quality, and other 

 characteristics of the entire 

 plant or of its roots, stems, 

 leaves, flowers, fruit, and 

 seeds. Physiological differ- 

 ences, such as early or late 

 maturing, ability to grow 

 in new conditions of soil 

 and climate, unusual sus- 

 ceptibility to or immunity 

 from the attacks of para- 

 sitic fungi, may appear and 

 are sometimes (Sect. 398) 

 of great economic impor- 

 tance. It is much easier to 

 perpetuate new varieties 

 unchanged in the case of plants propagated by vegetative 

 means, as by cuttings from roots or stems or by bulbs or tubers, 

 than in the case of those grown from seed. If a desirable 

 variety of potato is obtained by hybridizing and then plant- 

 ing seeds from the berries ("potato balls"), the hybrid can 



Fig. 339. A hybrid wheat and the parent 

 forms 



The hybrid is in the middle. It is somewhat 

 intermediate between tlie parents, being 

 nearly (but not quite) beardless like the 

 right-hand parent, with a length of head 

 intermediate between the two and with the 

 grains and their covering bracts stout, as 

 in the left-hand parent. Photograph by 

 Minnesota Agricultural Experiment Station 



