834 EXPERIMENT STATION RECORD. [Vol. 36 



The principal cultivated varieties of oats, together with their basic wild spe- 

 cies, are classified in eight groups, the elemental types being Avena nuda, A. 

 sterilis, A. ahyssinioa, A. strigosa, A. brevis, A. fatua, A. sativa, and A. sativa 

 orientalis. Fifty-five varieties are described within the three common specific 

 groups, A. sterilis, A. sativa, and A. sativa orientalis. The varieties are sys- 

 tematically arranged with respect to such morphological differences as appear 

 best to fulfill the requirement of constancy in inheritance and ease of observa- 

 tion and which should reasonably be expected to appear under other environ- 

 ments. The cassiflcation takes no account of differences in ability of varieties 

 to yield. 



An extensive bibliography is appended. 



Studies on oat breeding. — III, On the inheritance of certain glume charac- 

 ters in the cross Avena fatua X A. sativa, F. M. Surface {Genetics, 1 {1916), 

 No. S, pp. 252-286, pis. 2). — Continuing work previously noted (E. S. R., 33, 

 p. 38), this paper deals with the inheritance of certain characters of the flower- 

 ing glumes of the cross of A. fatua with A. sativa. 



A. fatua, known as the wild parent, possesses the following glume characters 

 which enter into consideration in this paper : The flowering glumes are black 

 or dark brown in color. The lower and upper grains of each spikelet bear heavy 

 . geniculate and twisted awns. Pubescence occurs on the back of both the upper 

 and lower grains, about the base of each grain, and on the pedicel of each 

 grain. The base of each grain is expanded into a broad sucker-like ring which 

 permits of easy shattering. 



The grain of A. sativa, the cultivated parent, is yellow. Awns are completely 

 lacking except in an ocasional spikelet, where the lower grain only may possess 

 a very weak awn. All pubescence on regions noted above is lacking. The base 

 of the grain is narrow and contracted and the grain does not shatter. 



The Fi plants are as a rule intermediates. The grain is brown in color, and 

 medium heavy awns are present on the lower grain of some spikelets, although 

 no awns are ever found on the upper grain. The lower grain is pubescent on 

 the back, but the upper grain is smooth. There is a tuft of hair at the sides of 

 the base of the lower grain, but not on the upper. The base of the lower grain 

 is intermediate in character, and that of the upper grain is like the cultivated 

 parent. The grain does not shatter. 



Data are available from 465 Fj plants, about 70 of which have been grown 

 in the Fa generation. Observations show that A. fatua carries genes for gray, 

 and possibly yellow, in addition to black. These colors segregate independently 

 of each other and the observed ratio closely approximates the expected ratio, 

 thus confirming Nilsson-Ehle's conclusion. 



The base of the grain in A. sativa is dominant to that of A. fatua and segre- 

 gates independently of color. The heterozygous condition in the lower grain can 

 be observed in the majority of plants. 



In this cross seven characters are correlated with the character of the base of 

 A. -fatua, as follows : Heavy awns on the lower grain, awns on the upper grain, 

 wild base on the upper grain, pubescence on the pedicel on the lower and on 

 the upper grain, pubescence on all sides of the lower grain, and pubescence on 

 the base of the upper grain. The Ft generation indicates that there is a degree 

 of linkage of the gene for pubescence on the back of the lower grain with that 

 for black color. 



The gene for pubescence on the back of the upper grain segregates independ- 

 ently of color, except that in the absence of the gene for pubescence on the lower 

 grain the former is unable to act. The gene for pubescence on the back of the 

 upper grain is linked with the wild base. 



