392 THE WHEAT PLANT 



monococcum $ was produced by Biffen in 1903. The F l plant was 

 damaged by Puccinia graminis and did not flower. Tschermak obtained 

 a similar hybrid. 



e. T. monococcum x T. vulgare. Cross pollinations of these two wheats 

 were made without result by Vilmorin in 1880. 



Tschermak records the .production of a few grains from a similar cross 

 in 1906 : the F x plants, however, do not seem to have been described. 



In 1911, after some failures, Vavilov obtained a single shrivelled grain 

 from the cross T. vulgare, var. erythrospermum ? x T. monococcum, var. 

 flavescens $ . The mother plant was an early, white, smooth-chaffed, 

 bearded wheat with red grain, the pollen parent being the variety of T. 

 monococcum known as " Engrain double." 



The hybrid (F x ) was a well- developed plant with five stems about 

 80 cm. high, ripening about two months later than either of the parents. 

 The ears were flattened and fragile, and the empty glumes strongly 

 keeled with conspicuous lateral nerves as in T. monococcum, while the 

 straw was hollow and the nodes glabrous as in T. vulgare. The plant was 

 sterile. Its glumes separated and remained apart several days at the 

 flowering period. The gynaecium and lodicules were apparently normal, 

 but the stamens were small with non- dehiscing anthers containing very 

 small, wrinkled, and transparent pollen-grains. T. monococcum is immune 

 to rust fungi, but the hybrid was readily inoculated with Brown Rust 

 (Puccinia triticind) and showed the dominant susceptibility of the maternal 

 parent. 



2. HYBRIDS OF T. dicoccum WITH OTHER WHEATS. 



a. T. dicoccum x T. monococcum (see p. 391). 



b. T. dicoccum x T. durum. I have no records of this cross. 



c. T. dicoccum x T. polonicum (see p. 394). 



d. T. dicoccum ? , var. atratum (Black Emmer) x T. sphaerococcum, 

 var. globosum $ (Punjab Type 5). 



Black Emmer has tall hollow straw, bearded flat ears, with blue-black 

 pubescent glumes, red grain, and is a late variety ; the Punjab wheat is 

 very early, and possesses very short, hollow straw, short square beardless 

 ears, with pubescent glumes and white, flinty grain. 



The hybrid which I obtained in 1917 had ears exactly like those of 

 the dicoccum parent, so much so that it appeared as if no crossing had 

 occurred. The F 2 generation consisted of a very varied series of red- 

 grained dicoccum forms, some with black glumes like the grandmother 

 and late, others of intermediate flowering period, with uniform white 

 glumes, uniform red glumes, white glumes with black margins and red 

 glumes with black margins respectively. In addition to the dicoccum 

 forms, there appeared one or two plants of a typical T. durum, with glabrous 



