3IO Journal of Agricultural Research voi.x. no. 6 



From the above discussion it is obvious that the quality and quantity 

 of awns is limited in this cross by the morphological constitution of the 

 lower flowering glume, which in turn is determined by the gene for 

 nakedness. In studying the inheritance of the awns, just as in the case 

 of the pubescence, it is necessary to disregard those plants with naked 

 or almost naked grain. On these naked plants there is no opportunity 

 for the somatic expression of strong awns, even if the gene for such awns 

 is present. 



In Table IX the two classes of plants included under the rubrics 

 "Intermediate hulled grain prevalent" and "Hulled grain" may be 

 classified accurately with reference to awn characters. On combining 

 these two classes of plants there are in all 322 plants, of which yj have 

 weak awns and 245 have medium strong or strong awns. This is appar- 

 ently a i-to-3 ratio, the expected numbers being 80 to 241.5. However, 

 again this result is based upon a selected group of F2 plants, and it is 

 possible that this group is not a random sample of the Fj population 

 with respect to a,wn characters. 



SUMMARY 



This paper contains a description of the Fj and F, generations of a 

 cross between a black hulled oat, Avena sativa patula var. Victor, and a 

 white naked oat, Avena sativa nuda var. inermis. 



The hulled parent is characterized by the presence of firm flowering 

 glumes (paleas) which adhere closely to the caryopsis, biflorous spike- 

 lets, black color of the glumes, strong awns, and a long but rather sparse 

 pubescence at the sides of the base of the lower grain. 



The naked parent is characterized by the presence of loose membranous 

 flowering glumes which do not adhere to the caryopsis, multiflorous 

 spikelets, white or light yellow glume color, almost total absence of awns 

 and the absence of pubescence. It is possible that the absence of awns 

 and of pubescence is due to the inability of these characters to express 

 themselves on the thin membranous glumes. 



The Fi generation is distinctly intermediate in most characters. In 

 regard to the glumes, both naked and firmly hulled grain as well as 

 intermediate forms are found on the same panicle and even in the same 

 spikelet. As shown in Table I, the spikelets near the top of the panicle 

 are either entirely naked or nearly so, while those spikelets near the base 

 of the panicle tend to be firmly hulled. A similar but less marked rela- 

 tion is to be observed between the spikelets at the tip and base of each 

 whorl. 



In the F2 generation a large number of intermediate forms appear. 

 In addition to the two parental hull types, four intermediate classes 

 were distinguished. These intermediate forms contain all gradations 

 from the plants with perfectly hulled grain to the perfectly naked 

 forms. 



