2 BULLETIN 622, U. S. .DEPARTMENT OF AGRICULTURE. 



done much to stimulate interest in barley. At the same time a demand 

 for more detailed information on all our crops has developed. Plant 

 problems, especially studies in variations and inheritance, are being 

 persistently attacked. When this new interest was directed toward 

 barley, it immediately became apparent that this crop, because of 

 the unusual clearness of the varietal distinctions, was exceptionally 

 well suited both to student instruction and to genetic studies. This 

 clearness comes in part from the very broad limits of the group. 

 The variable characters are numerous and the separations sharp. 

 Few cultivated crops present such contrasts as hulled and naked 

 kernels, 1 awned and hooded lemmas, fertile and infertile lateral 

 florets, etc. The number of factors, coupled with the fact that all 

 forms are perfectly fertile when crossed with each other, has resulted 

 in a large number of easily distinguished varieties. The relative 

 ease of subdividing the species makes the crop a profitable one to the 

 student, and the clefiniteness of its varieties makes it equally useful 

 to the plant breeder. 



The lack of available literature and the confusion existing as to 

 the identity of the various forms have been a real handicap to stu- 

 dents and plant breeders alike. Studies in crop plants must include 

 a comprehensive summary of the forms and types of each crop. This 

 is a necessity for that familiarity with the crop which both student 

 and agronomist should possess and is essential to a proper under- 

 standing of the publications of others dealing with the subject. 



At present American literature contains no such summary. In- 

 deed, the only work in English which attempts to present a complete 

 arrangement of the forms is Beaven's "Variety of Barley" (1902). 2 

 This is out of print and is to be found in very few libraries. In 

 French there are the works of Heuze (1872, 1896-97), and in Ger- 

 man those of Kornicke and Werner (1885), Voss (1885), and Atter- 

 berg (1899). The utilization of these and other more fragmentary 

 publications is difficult. Frequently they are not available, and even 

 if at the disposal of the investigator they present as many different 

 methods of treatment as there are authors. In some instances the 

 departures are so revolutionary that serious confusion has resulted. 



The aims of this paper are (1) to coordinate the various schemes 

 of classification and to reconcile them as far as possible, (2) to make 

 available the work that has already been published on barley and 

 to suggest modifications to obtain a more logical arrangement of the 

 varieties, (3) to add the several new forms of barley which have been 



1 The word kernel is used throughout this publication to indicate the naked kernel 

 (caryopsis) in the naked varieties and the kernel with lemma and palet attached 

 (caryocist) in the hulled varieties. It was found too cumbersome to use the more limited 

 terms, as they required repeated explanations. 



-For complete citations, see " Literature cited," p. 31. 



