HYBRIDIZATION 



347 



143, 5. The essential organs are completely enclosed by two bracts, 

 the floral glume or lemma, which bears an awn in bearded varieties, and 

 the smaller palea. The lemma and the palea open for a short time during 



FIG. 144. Hybridizing wheat. Note position of operator and his equipment, con- 

 sisting of a box containing strips of paper and pins for covering the wheat heads and tags 

 for labeling, a flask of alcohol for sterilizing the hands and instruments, a pair of forceps and 

 a scalpel. Pollinated heads which have been wrapped and labeled are shown at the left. 



anthesis, but as a rule some pollen is shed upon the stigma before the 

 flower opens. The flowers remain open only a short time in cool climates 



11, pollen grains, round and smooth, 55 micro-millimeters in diameter. 



12, ovary and stigma just prior to flowering; 13, at the time of flowering; and 14, 

 shortly after flowering. 



15, 16 and 17, the mature seed; o, the ventral side; 6, the dorsal side; c, the germ or chit; 

 s, the stem end of the germs; r, the root end; e, outer layers or bran; d, the incurved surface 

 of bran on the ventral side of the seed. The white portions of 16 and 17 are the floury 

 interior consisting of cells containing the gluten and starch from which white flour is made. 

 (After Hays and Boss, Minn. A. E. S.) 



