35 6 THE WHEAT PLANT 



however, observed the occurrence in Australia of what he termed " grass- 

 clump plants " among the progeny of many of his hybrid wheats. Richard- 

 son also reports their appearance among his crosses in the same country, 

 and Cutler obtained a single specimen, which he describes as a " dwarf 

 wheat," in a plot of Marquis wheat in Saskatchewan. These forms differ 

 from the ordinary crop in producing dense, compact clumps of leaves, 

 from which arise only a few short culms with small ears. Farrer states 

 that they appear among crosses between widely different types of T. 

 vulgar e only and are first seen in the F 2 generation, though in one instance 

 (a cross between " Bokhara desert " wheat and a Fife-Indian variety) all 

 the F! plants (four in number) were " grass-clumps." 



There is, I think, little doubt that these are segregates of the ordinary 

 " winter " type, requiring a longer period for completion of their growth 

 than the Australian climatic conditions allow, and are not true " dwarf " 

 plants ; they behave under these conditions exactly as " winter " forms 

 of Bread Wheat do in this country when sown too late in spring or summer 

 to produce ears in the same year (see p. 90), and if protected from drought 

 would doubtless produce normal culms and ears in the following season. 



BUD SPORTS. This class of variation is exceptionally rare among 

 wheats. 



Akerman describes four examples discovered among the descendants 

 of hybrids of T. vulgare. Larger or smaller portions of the ears of these 

 sports have empty glumes which resemble those of T. Spelt a in form, 

 nervation, and close investment of the grain. 



In one of them found in the F 2 of the hybrid Iron x Thule II. wheats, 

 the ear had speltiform empty glumes on one side and normal vulgare 

 glumes on the other. 



A similar sporting ear was obtained on a plant with five ears, four of 

 which were normal, the plant being one of the F 5 progeny of the hybrid 

 Brown Schlanstedt x Borsum (a Norwegian spring wheat). From the 

 same cross another plant arose having three ears, two normal and one 

 with the upper part speltoid, and the lower portion speltoid on one side 

 and normal on the other. 



In the fourth example all the spikelets of the upper part of the ear 

 possessed speltiform empty glumes, but in the four lowest spikelets one 

 of the empty glumes of each spikelet was speltiform and the other normal 

 vulgare. 



The speltoid empty glumes in all these cases are erect and nearly 

 parallel to the rachis, the corresponding opposite glumes being arranged 

 almost at right angles to them. The affected spikelets are turned to one 

 side in a manner similar to some of those in Fig. 179. 



Akerman regards these as periclinal or sectorial chimaeras. Three of 

 the sports, it was suggested, were normal plants surrounded by a hetero- 



