246 THE WHEAT PLANT 



keel, but possessing 9-15 fine nerves, which converge at the tip into the 



terminal awn. 



The awns are stout, yellowish-white, red, 

 or black, from 8 to 16 cm. in length, triangular 

 in section, the angles from the base to the 

 apex being set with scabrid forward-pointing 

 projections. 



In a few varieties the awns diverge slightly 

 outwards ; usually, however, they are parallel 

 to each other and to the long axis of the ear. 

 Several kinds shed their awns when the grain 

 is ripe. 



As a rule only the two lower flowering 

 glumes of the spikelet bear long awns ; those 

 of the third and higher flowers are much 

 shorter or altogether missing. 



The palea is membranous and of the 

 normal bi-nerved form. 



The typical grain is white, yellow, or 

 red, large, broad, and plump, though some- 

 times flattened on one side by pressure of 

 the empty glume, blunt or truncate at the 

 " brush " end, with a high dorsal arch or 

 hump behind the embryo. The furrow is 

 shallow and the ventral flanks rounded in 

 w r ell-grown grains (Fig. 153). 



In a few forms the caryopses are narrower 

 towards the apex, though rarely so much as 

 in T. durum and T. dicoccum. In a small 

 number the dorsal arch is reduced, the grain 

 then approximating to that of T. vulgar e. 



In some seasons, and especially when the 

 %\jf* cr P i s sown late, the grains at harvest ex- 



hibit a somewhat rough surface, and are 

 poorly filled ; this result is most evident 

 FIG. 154. Grains of the spike- among varieties possessing the largest grains. 



ISef XeaffT ' L$ The emb <T is comparatively small and 



(Blue Cone) (nat. size). the endosperm usually opaque and starchy, 



although in a few forms it is flinty. 



Measurements of grains taken from the middle of the ear of thirty- 

 eight varieties gave the following results : 



