HORDEUM 139 



weak to force the glumes apart. In four-rowed barley, 

 in which open flowers are the rule, lodicules are well 

 developed. It would seem, then, that in four-rowed 

 barley and two-rowed nodding barley, there is a possi- 

 bility of cross-pollination, while in six-rowed, peacock, 

 and two-rowed erect barleys this possibility is excluded. 

 However, very few positive cases of natural hybridization 

 of barleys have been observed. The reason ioj this prob- 

 ably is that the styles are short and do not protrude beyond 

 the glumes. Rimpau examined a large number of sorts, and 

 in all, found but eight sure cases of crossing, and these were in 

 four-rowed barleys. Self-pollination is the rule, which means 

 that under field conditions there is little danger that a pure 

 strain will become impure through the introduction of 

 characters brought in by the pollen grains of undesirable 

 strains. 



Blooming in barley begins between 5:30 and 6:00 a.m., 

 increasing in intensity up to 8:00 a.m. Very little blooming 

 occurs in the middle of the day. There is a slight amount 

 between 3 and 5 o'clock in the afternoon, but by 8 in the 

 evening all blooming has ceased. 



As in all cereals, blooming is dependent upon the weather. 

 Barleys that normally bloom with open glumes on a day with 

 high temperature and dry atmosphere, may bloom with 

 closed or only sUghtly open glumes on a cool, moist day. 



Fertilization and Maturing of Grain. — The immature grain 

 has much the same structure as that of wheat. Kudelka 

 finds that, in barley, the chlorophyll-bearing layer consists 

 of two rows of cells, however. As, in wheat, there is an 

 early resorption of the two layers of the outer integument, 

 and of pericarp and nucellar cells. The barley grain passes 

 through the milk-ripe, yellow-ripe, full-ripe, and dead-ripe 

 stages. 



