2 Bulletin- 1334, tj. s. depaktmei^t of ageicultuee 
of some varieties can not be certain, but they feel that they are sub- 
mitting something tangible which will be of use to the agronomists 
vrho have assisted them. 
As far as possible all the ^delds obtained in field plats in the United 
States have been included. In some instances plat yields have been 
rejected because of failure to establish the identit}^ of the variety or 
because of accident of season that vitiated the results. Doubtless 
there are included many results that the station agronomists would 
desire omitted. However, as one of the main purposes of tliis bulletin 
is the defining of ecological boundaries of various types of barleys, it is 
thought that these yields are valuable, at least from that standpoint. 
While the writers of this bulletin may point with some justice to 
many tedious months of compilation and to an endless effort of iden- 
tification, the real authors of this bulletin are the agronomists of the 
various States. It is only by theu^ unselfish donation of data that 
this compilation has been made possible. That all States are not 
represented in the compilations is due not to any unwillingness on the 
part of their officials, but to the fact that they have not grown barley. 
The agronomists of every barley-grov>dng State but one have made 
available all their station results on barley. They have not only 
granted the use of these data, but they have extracted the results and 
histories, which has been no small task. At a few of the stations 
some of the results were secured by them in cooperation wdth the 
United States Department of Agriculture, but even in the coop- 
erating States the material furnished was far more than that jointly 
obtained. The writers desire hereby to express theu' appreciation of 
these many courtesies received from State agronomists. 
BARLEY GROWING IN AMERICA 
The demarcation of areas of adaptation is obviously an ecological 
study. The usual method of studying variation in plants is by 
classifying them as to their morphological characters. Fortunately, 
groups of varieties which vary in their climatic requirements also 
vary in their taxonomic features as weU. In either case the grouping 
is merely a convenient method of study. When large numbers of 
varieties are considered the group limits merge, vdiether the separa- 
tions be made on an ecological or a morphological basis. Even so, 
the discussion is materially facilitated b}^ the use of these distinc- 
tions, and in most cases there is no confusion. 
VARIETAL GROUPS 
There are several ecological groups of barley which are well marked 
when typical varieties are considered. The most common of these 
in the United States are the Manchurian, wliich embraces most of 
the 6-rowed barleys of the temperate plains of Europe and Asia, 
and the Coast group, which includes many 6-rowed barleys from 
North Africa and Spain. Other well-known groups include the Chev- 
alier and Thorpe of England, the Hanna of Bavaria and Austria, 
the Sm>Tna group of Asia Minor, and the hull-less forms of Central 
Asia. The differences between Chevalier, Gold, Thorpe, Manchuria, 
and Coast varieties are very apparent, and there is no overlapping. 
These barleys are adapted also to definite sets of ecological condi- 
