210 



THE WHEAT PLANT 



along the margins with 

 hairs, and bears a frontal 

 tuft at the base of each 

 spikelet. 



The spikelets are 5- to 

 y-flowered, those of square 

 ears ripening three or four 

 grains, those of com- 

 pressed ears usually only 

 two ; they are from 10 to 15 

 mm. long, 8- 1 5 mm. broad, 

 and 4-5 mm. thick. 



The empty glumes are 



FIG. 139. Grains of Macaroni wheat (T. durum), 

 front, back, and side views (nat. size). 



glabrous or hairy, the length and amount of 

 the hair varying considerably. The colour 

 is yellow, red, or blue - black in various 

 shades. Those of the lateral spikelets are 

 8-12 mm. long, unsymmetrical, the outer face 

 somewhat flat and measuring from the midrib 

 to the outer edge 4-5 mm., the inner portion 

 being 2-3 mm. wide. A prominent keel runs 

 from the base to the tip. The apical tooth, 

 which may be acute or blunt, is of variable 

 length ; the lateral secondary tooth in which 

 the strong nerve on the outer face terminates 

 being usually short or missing : the various 

 forms of empty glumes are illustrated in Fig. 



138- 



The flowering glumes are thin and pale, 

 rounded on the back with 9-15 nerves, the 

 two lowest of each spikelet having long awns, 

 measuring in some cases as much as 20-23 

 cm., those of the upper flowers of the 

 spikelet usually having a length of -5 to 4 cm. 

 long. 



The awns are white, red, or black, the 

 latter tint, as in T. turgidum and other wheats 

 (see p. 105), being developed to the greatest 

 extent in dry bright weather, frequently failing 

 to appear in dull humid seasons ; they are 



FIG. 140. Grains of the spike- 

 lets on one side of an ear of 

 Macaroni wheat (T. durum) 

 (nat. size). 



