FIELD CROPS. 39 



strains the first tiller appears decidedly later tlian the fourth leaf. In others 

 it appears earlier. In some the tillers are all produced within a short time; in 

 others the process is extended over several days. 



" The emergence of the awn is an extremely important note, as it occurs at a 

 time in the life of the plant when such an observation is of great value. The 

 development is usually normal at this time^ as hot weather and drought have 

 ordinarily not j'et had any effect. The emergence of the awn has been found 

 to be far more accurate and more easily obtained than tlie date of heading. 

 The precocity of the strain at the time of the emergence of the awn is a herit- 

 able character. The date of ripening is, unfortunately, often influenced by 

 season and, while a valuable character, is less dependable than the emergence 

 of the awns. A comparison of the development during all stages serves to re- 

 veal many differences not apparent when each stage is taken separately. 



"The length of the culm is of use as a local breeding note, but the variations 

 are not parallel when strains are planted in totally different areas. The 

 diameter of the culm is not serviceable, because nearly related barleys have 

 culms of approximately the same size. The thickness of the walls of the culm 

 is a note with a large experimental error and therefore of questionable utility. 

 The degree of exsertion of the spike is sometimes a varietal character but is 

 not often useful. The number of culms per plant is to some extent a varietal 

 character, but selections are so affected by season and location that it is very 

 difficult to use. The width of the leaves is useful in group distinctions and 

 sometimes in varietal separations. The length of the leaves is much less de- 

 pendable, and is serviceable only in rather extreme tyijes. The number of 

 leaves varies with the groups, but usually closely related strains possess ap- 

 proximately the same number of leaves, 



" The density of the si^ike may easily be made the basis of many separations. 

 Often varieties that show no other differences are widely dissimilar in density. 

 The density of a selection varies somewhat with season and location, but the 

 mean is always shaii^ly defined and the fluctuations more or less parallel. In 

 some strains all spikes conform closely to the mean, in others the range is 

 greater. This seems to be a varietal character and is constant even when the 

 plantings are made under widely varying climatic and soil conditions. 



'' The established taxouomic groups based on relative fertility were found to 

 be invariable under all extremes of American climate. The natural varieties in 

 the deficiens group of Abyssinian barleys seem more extensive than most classi- 

 fications have indicated. From barleys of this same region a group with a 

 peculiar habit of floret abortion has been isolated. The length and the width 

 of awns vary, but they are so correlated with other taxonomic characters that 

 they are seldom useful in close separations. The tenacity of the awn is fre- 

 quently a varietal character unaffected by location or season. The chai-acter 

 of the basal bristle has been found to be stable under American conditions. 

 The toothing of the inner part of dorsal nerves is much more variable, but the 

 variation is usually within defina*ble limits. The length of the kernel, while 

 influenced by climate, is a varietal character. The lateral and dorsoventral 

 diameters of the kernel are varietal characters to some degree, but tliey are so 

 influenced by conditions of growth as to become confusing in most instances. 

 The composition of the grain is a varietal character, but it is one dominated by 

 climate, 



" There are two coloring materials in barley : One, anthocyanin, is red in its 

 acid and blue in its alkaline condition. The other, a melaninlike compound, is 

 black. The pigments may occur in the hulls, the pericarp, the aleurone layer, 

 and occasionally in the starch endosperm. The resulting colors of the grain 

 are quite complicated. White denotes the absence of all pigment, a heavy de- 



