6 THE SMALL GRAINS 



(auricles), one from each edge of the leaf, which partially 

 or entirely clasp the culm. They are well developed on 

 barley, but are lacking on oats. On young wheat plants 

 they often bear a number of hairs. 



The leaf-blade is usually narrow-linear or linear-lanceo- 

 late and often is twisted. In rye and wheat it is twisted 

 to the right. In oats it is twisted in both directions, in 

 one direction above and in the other below. Fibrovascular 

 bundles (" nerves ") parallel each other throughout the 



FIG. 3. Part of cross-section of a wheat leaf : A, mesophyll ; B, in- 

 tercellular space ; E, epidermis ; H , chlorophyll grains ; O, fibrovascular 

 bundle ; N, vessel ; S, stoma and guard cell. (X 71.) 



blade, ending at the edge, and give firmness to the leaf. 

 The primary bundles are accompanied on one or both 

 sides by bundles of hard tissue (sclerenchyma) . 



The epidermis of the leaf in many cases contains much 

 silica in its cell- walls, which stiffens the blades. Wedge- 

 shaped bulliform cells, arranged in fan formation, 

 between the nerves, expand and force the blade to open. 

 The stomata or " breathing-pores " are in longitudinal 

 rows and each surrounded by four cells, two of these being 

 long, narrow guard cells. In the cases of wheat and oats, 

 at least, these stomata are more abundant in the upper 

 epidermis (Fig. 3). 



4. Inflorescence. By the branching of the upper 

 portion of the stem, inflorescence originates; it may 



