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



division of the appendages to the lemma and one of the outer glumes 

 have been again separated into two subdivisions. The resulting 

 number of possible varieties is in consequence very large. 



FERTILITY. 



Barley, being a typical Hordeum, produces three single-flowered 

 spikelets at each node of the rachis. In the 6-rowed forms, all three 

 of these are fertile. In the 2-rowed only the central spikelet of each 

 three is fertile. There are four degrees of fertility, two in the 

 6-rowed and two in the 2-rowed forms. The four divisions are 

 based upon characters of the lateral florets, the central floret being 

 the same in all. The lateral florets of normal 6-rowed barleys are 

 completely fertile and awned or hooded. The common 2-rowed 

 barleys are characterized by sterile lateral florets, which are awnless 

 and normally rounded at 'the tip. In the intermediate barleys the 

 side florets are fertile, but the resulting kernels are usually small 

 and the tips are without awns. Ordinarily the lemmas are rounded, 

 but occasionally they bear bristlelike projections. In most varieties 

 of this group only part of the lateral florets are fertile. The fourth 

 division is distinguished from the common 2-rowed form by a still 

 further reduction of the side florets. This reduction may be carried 

 to the point where only a single outer glume is present. Usually 

 the spikelets are represented only by the outer glumes and rachilla, 

 the floral glumes and sexual organs being entirely aborted. In some 

 strains the lemma is present, and in a very few there are traces of 

 the p'alet. Rudimentary ovaries and stamens are never found. 

 Barleys in which sterile ovaries, rudimentary stamens, or well- 

 developed palets appear are classed as normal 2-rowed forms. 



ADHERENCE OF THE FLOWERING GLUME. 



The distinction between adherent and nonadherent flowering 

 glumes is the sharpest and most easily determined of the six. It 

 separates the barleys into the hulled and naked forms. In the 

 hulled varieties the ovary grows fast to the lemma shortly before 

 maturity. In the naked sorts this union does not take place, and 

 when the spikes are thrashed the kernel thrashes free from the 

 glume, as in wheat. 



OUTER GLUMES. 



Each floret in barley is subtended by a pair of outer glumes. These 

 are normally narrow, lanceolate bracts, with short, bristlelike awns. 

 In rare cases they are expanded and the length of the awn increased. 

 Those varieties with wide outer glumes have been further separated 

 by some authorities, because in some instances all six of the outer 

 glumes at a node are widened, whereas in other cases only the two 



