THE INFLORESCENCE 



and hidden from view ; in others, they are widely separated and the rachis 

 visible between the adjacent spikelets (cf. Figs. 

 188 and (i) 180). 



In the majority of varieties the distribution 

 of the spikelets along the rachis is fairly uni- 

 form, but in some ears the spikelets are 

 especially crowded at the tip and arranged in 

 a lax, open manner towards the base (i, Fig. 

 189) ; such ears are spoken of as " clubbed," 

 though the name " Club wheat " is used for 

 the race T. compactum, in which the ears are 

 very short, with spikelets closely set along 

 the entire length of the rachis. 



Viewed from the side the spikelets stand 

 out from the rachis, making with the latter an 

 angle of 2O-8o or more, the smaller angle 

 being found in lax-eared forms, the larger in 

 dense compact ears. 



Each spikelet consists of a delicate flat- 

 tened and jointed rachilla (a, Fig. 76) which 

 bears two opposite rows of alternate solitary 

 flowers hidden between chaffy bracts or 

 glumes. The glumes are either glabrous or 

 covered with soft hairs, the colour when ripe 

 being creamy white, yellow, red, brown, or black. 



The number of flowers in a spikelet varies 

 from 3 to 9, of which one or more of the upper 

 ones are usually imperfect and sterile. 



At the base of the spikelet are two opposite 

 rigid boat-shaped bracts, the empty glumes, 

 which in all wheats, except T. polonicum, are 

 shorter than the rest of the spikelet, and in 

 lateral spikelets the parts right and left of the 

 midrib are dissimilar in size and shape. Their 

 size, shape, texture, form of keel, and terminal 

 tooth are constant characters, of high taxo- 

 nomic value. In some wheats they are 

 keeled throughout their whole length, in 

 others the projecting keel extends only a short 

 distance from the apex, the lower portion 

 being rounded ; each possesses several nerves, 

 the central strongest one dividing the glume into two unequal halves, 

 of which the outer is the broader. 



FIG. 77. Disarticulation of the 

 rachis of a form of T. aegilo- 

 poides. 



