34 



BREEDING CROP PLANT X 



Group 4. Vegetatively propagated: Potatoes, sugar cane, 

 many fruits. 



NATURAL CROSSING WITH SELF -FERTILIZED PLANTS 



Flower types are adapted for various degrees of self- or cross- 

 fertilization. This in itself is a field in which much study might 

 be made. The plant breeder, however, is chiefly interested in 

 the final result. 



FIG* 10. Natural hybrids in wheat. 1. From right to left: Spike of a pure 

 variety produced from a cross of Turkey winter wheat and Wellman's Fife spring 

 wheat. This is a bearded variety with smooth chaff. The progeny of a single 

 plant of this variety gave 48 bearded, smooth chaffed plants and 2 plants with 

 intermediate (tipped awns) and hairy chaff. 2. From right to left: Preston 

 spring wheat; an F\ natural hybrid with intermediate awns and hairy chaff. 

 The parental varieties from which these natural hybrids were obtained were 

 grown alternately with Haynes Blue Stem the preceding year. 



Wheat.* The individual florets of wheat and barley are 

 much alike. The envelope of a floret of wheat, for example, 

 consists of the flowering glume or lemma and an inner glume or 

 palea. The sexual organs consist of a pistil with a two-branched, 



1 POPE has reviewed much of the literature for cereal crops. See Journ. 

 Amer. Soc. Agron., 8: 209-227. 



