VARIATION 



359 



viii. SUPERNUMERARY SPIKELETS. These sometimes arise singly by the 

 side of a normal spikelet and arranged at right angles to it. Both spring 

 from the same notch of the rachis. 



Additional spikelets are also frequently found growing from the rachis 

 immediately below the points of insertion of the normal spikelets and 

 generally arranged parallel to them (i, Fig. 216). In some cases they 

 produce one or two grains, but are often rudimentary, consisting only of 

 minute misshapen glumes. 



These variations, which I have found most often 

 in Chinese vulgar e wheats, occur chiefly in ears of 

 the latest tillers, the ears which develop first being 

 usually quite normal ; the variation does not appear 

 every season, though a form which has once shown it 

 may produce it again. 



ix. AWNS. I have not observed many variations 

 in the structure or general morphology of the awns 

 of wheat. 



In a Persian form of T. vulgar e the short awns of 

 the flowering glumes of some of the spikelets some- 

 times have a thin membranous outgrowth on each 

 side, about half-way between the tip and base of the 

 awn (Figs 179, 217). The peculiarity is not constant. 



In several Central Asiatic forms of beardless T. vulgar e the short awns 

 at the apex of the ears are often strongly curved and sometimes bent into 

 the form of a hook. 



x. TWIN GRAINS. Malformations of the parts of the flower are rare 

 in wheat. The only case recorded appears to be that figured by Caron- 

 Eldingen, of a twin grain with two embryos, developed from two united 

 ovaries. 



FIG. 217. Flowering 

 glumes of a Semi- 

 retchensk form ( T. 

 vulgare) (see 2, 

 Fig. 179)- 



