RIVET OR CONE WHEAT 245 



nerved, the portion from the midrib to the outer edge being 4-5 mm. across, 

 the inner membranous part being half as wide. The strong apical tooth in 

 some varieties is acutely pointed, i-i'5 mm. long, and curved inwards, in 

 others short and blunt. A well-marked keel runs from the base to the 



HIM 



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FIG. 152. Empty glumes of Rivet wheat (T. turgidum) ( x 2). 



tip, and a more or less prominent lateral nerve is present on the outer 

 broad half of the glume, running from the base to a point close to the 

 apical tooth, where in some forms it terminates in a short secondary 

 tooth (Fig. 152). 



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FIG. 153. Grains of Rivet wheat (T. turgidum), front, back, and side views (nat. size). 



The empty glumes of the terminal spikelet are ovate and more or less 

 symmetrical (Fig. 78). 



The flowering glumes are thin, fragile, and pale ; even in the black- 

 eared varieties the dark tint is not developed in the part covered by 

 the empty glume. They are oval, inflated, and boat-shaped, without a 



