MODE OF REPRODUCTION IN RELATION TO BREEDING 35 



fl 



feathery stigma and of three stamens with anthers, all of which 

 are enclosed by the lemma and palea. Opposite the base of the 

 palea are two tiny sac-like organs, lodicules. The increase in size 

 of these organs due to water absorption causes the flower to open. 

 This occurs when the stigma is receptive and at this time the 

 elongation of the filaments causes the 

 anthers to protrude from the glumes, 

 when they promptly dehisce. The 

 process of blooming is very rapid and 

 seldom requires more than 20 

 minutes. Leighty and Hutcheson 

 (1919) state that the opening of the 

 glumes from beginning to completion 

 may not require more than one 

 minute, that the anthers may be ex- 

 truded and emptied of their contents 

 within two to three minutes and the 

 glumes again become tightly closed 

 at the end of 15 to 20 minutes. 

 Kirchner (1886) states that about 

 one-third of the pollen falls inside 

 the flower. As the pollen is blown 

 around the field by the wind it is 

 easily seen that natural crossing 

 may sometimes occur. 



Investigators differ in their be- 

 liefs regarding natural crossing in 

 small grains. De Vries (1906) 

 says " wheat, barley and oats are 

 self-fertile and do not mix in the 

 field through cross-pollination . ' ' 

 Biffin (1905) states that he has never 

 observed a case of cross-pollination 

 in wheat; while Fruwirth (1909) lists 

 several German breeders who have 

 given instances of natural crosses. Fruwirth says 

 ties can be cultivated 

 Nilsson-Ehle (1915), in Sweden, has found that some varieties 

 show a much greater amount of natural crossing than others. 

 Howard and others (19 10a), in India, carefully studied natural 

 crossing in wheat for several years and recorded 231 natural 



FIG. 11. Natural wheat-rye 

 hybrids. Two spikes of parent 

 wheat varieties are shown on the 

 outside with hybrid spikes on the 

 inside. (After Leighty.) 



" wheat varie- 

 side by side for years without mixing." 



