THE INFLORESCENCE 103 



full extent on exposed parts of the ear, the portions of the flowering 

 glumes covered by the empty glumes being pale red or light yellow. 



Among certain forms of T. dicoccoides, T. aegilopoides , and T. durum 

 hybrids the colour is more or less irregularly distributed in lines or patches 

 over the empty glume ; in others it appears only as a single dark line 

 along the outer margin of the glume, the latter character being con- 

 spicuous in some forms of T. turgidum, var. melanatherum, and in many 

 hybrids of T. dicoccoides, T. dicoccum, and T. durum. 



It is only in hot, bright seasons that the melanotic pigment is fully 

 developed ; in cooler damp years the glumes of black-chaffed varieties, 

 especially those belonging to T. vulgare and T. Spelta, are generally an 

 ashy-grey tint. 



The glumes are either glabrous or more or less clothed with hairs. 

 Sometimes the hairs are few and confined to the nerves, but in many 

 forms they cover the whole surface with a tomentum or felt of varying 

 density. The hairs are unicellular and terminate in a fine point. 



In T. aegilopoides and T. monococcum the hairs are very slender, from 

 16 to -32 mm. in length, and of nearly uniform diameter. Both long hairs 

 and short ones, about one quarter the length, are found on the glumes 

 of T. dicoccoides and T. dicoccum. the long ones measuring from -5 to -65 

 mm., the short ones averaging about -12 mm. 



Similar slender silky hairs of two fairly distinct sizes occur on the 

 chaff of T. durum and T. turgidum, the long ones being -6- -8 mm. in 

 length, the shorter only -i6--2 mm. in T. durum, and -2- -32 in T. 

 turgidum (a, Fig. 79). 



The hairs on the glumes of the pubescent varieties of typical vulgare 



a b 



FIG. 79. Hairs from the glumes of (a) T. durum, (b) T. vulgare (x 40). 



wheats vary also in length, but the difference between the long and the short 

 ones is not so great as in the races of wheats already mentioned ; moreover, 

 they are readily distinguished by their stouter appearance, greater width, 

 and thicker walls (b, Fig. 79). The long hairs usually measure from 

 6 mm. to i -2 mm. in length, the short ones from -2 mm. to -3 or -4 mm. 

 In some vulgar es, typical stout vulgare hairs are found mixed with 

 fine, slender, short ones, resembling those of T. durum, a similar mixture 



