26 BULLETIN 137, U. S. DEPARTMENT OF AGRICULTURE. 



such varieties does not come about through the breaking of that 

 organ, but by its being loosened from the glume. It is the tissues of 

 the glume that give way, and lack of persistence is thus in reality a 

 character of that organ. 



In the hooded barleys the awn of the flowering glume is replaced 

 by a trifurcate appendage. This is of evident monstrous origin and 

 is connected with the awned class by no true intermediates. The 

 exact nature of the appendage is not clear. In structure the parts 

 appear to be the result of vegetative stimulation, and they are glume- 

 like in appearance. The fact that they are three in number and that 

 they bear rudimentary florets indicates that they are a partial repeti- 

 tion of the spikelets of an internode, the leafy segments being the 

 flowering glumes. The character is absolutely constant. 



THE BASE OF THE FLOWERING GLUME. 



The method of the attachment of the lemma, or flowering glume, 

 to the rachis has been shown by Atterberg ( 1 ) to be a distinguishing 

 mark between the erectum and nutans groups. In the nutans group 

 the grain (and therefore the flowering glume) is attached by a very 

 constricted band of tissue which, when separated, leaves the proximal 

 extremity smooth. The surface is oblique to the long axis of the 

 grain and presents a small horseshoe-shaped depression just above 

 the line of attachment. In the erectum group there is more than one 

 variation of form, but all are centered around an attachment to the 

 rachis that is much broader than in nutans and the depression is 

 absent. When the central nerve of the dorsal glume is not too large 

 and continued too far through the base, a transverse crease is found 

 just above the attachment. The 6-rowed barleys are separated by 

 the same means. 



ADHERENCE OF THE FLOWERING GLUME TO THE PERICARP. 



The normal form of barley is one in which the glumes are grown 

 fast to the pericarp. There are numerous varieties in which this 

 union does not occur. These constitute our naked barleys. Both 

 forms are absolutely stable. The character offers no opportunity for 

 minor distinctions, unless it be in such cases as Princess, which the 

 Swedish Plant-Breeding Association maintains has a low weight per 

 bushel, owing to an abnormally loose attachment of the glumes. 



THE SVALOF CHARACTERS. 



In 1889, Neergaard (19), of the Swedish Plant-Breeding Associa- 

 tion at Svalof , announced the most important discovery in the classi- 

 fication of the lesser groups of barley that has ever been brought to 

 the attention of the world. Xot only was it of exceptional intrinsic 

 value, but it acted as a great stimulus in the study of elementary 



