402 THE WHEAT PLANT 



somewhat dense, beardless form of T. vulgar e (said to be a hybrid), with 

 Rood Koren, a bearded T. compactum from South Africa. 



The l plants had squarish compact ears of intermediate length with 

 a few awns about i inch long at the tip, the compactum parent being fully 

 bearded with awns 2^-3^ inches long. 



In F 2 four forms appeared, viz., short-eared, long-eared, awnless, and 

 awned, the numbers of each being : 



664 awnless, 207 awned ; 643 short-eared, 229 long-eared, the ratios 

 approximating to the monohybrid 3 : i type. 



Little variation in length and density of ear was observable among 

 the long-eared segregates, but the short-eared forms were less uniform, 

 and a few plants had exceptionally compact ears. 



The long-eared, beardless plants of this F 2 generation gave in F 3 

 almost entirely long-eared, beardless progeny, the bearded F 2 plants 

 giving a similar preponderance of awned, long-eared descendants. 



The short-eared, bearded plants of F 2 gave mostly bearded progeny 

 in F 3 , the length of ear showing considerable variation : the corresponding 

 short-eared, beardless forms proved to be similar in constitution to the 

 Fj hybrid, and, like it, gave four types in F 3 . 



iv. T. compactum, var. Humboldtii 9 x T. vulgare (Epp Wheat). 

 Rumker crossed these wheats, the F l being a typical " Squarehead " 

 intermediate in ear-density between the two parents. In F 2 segregation 

 was of the monohybrid 1:2:1 type, this generation consisting of 21 Epp : 

 37 Squarehead : 20 compactum. 



A Squarehead of F 2 split similarly in F 3 , giving 18 Epp : 49 Square- 

 heads : 21 compactum. 



v. T. vulgare $ (White Frankenstein) x T. compactum 3 (White Velvet 

 Igel). This cross obtained by Rimpau gave more complex results. 

 The F! generation consisted of four plants, one, a typical beardless 

 Squarehead, the others produced both beardless long and lax ears and 

 Squarehead-like ears on the same plants. 



In F 2 were obtained five forms, viz. : 



a. 21 beardless Squareheads. 



b. 12 beardless, dense-eared, not typical Squareheads. 



c. 5 bearded Squareheads. 



d. 8 lax-eared, beardless plants of the Frankenstein type. 



e. i lax-eared, bearded plant. 



38 dense : 9 lax (4 : i). 



41 beardless : 6 bearded (7 : i). 



Two of the beardless Squarehead plants (a) gave all bearded descendants 

 in F 3 . 



