CARBOHYDRATES 



149 



» The following standard abbreviations are used in this table. The monosaccharide radicals are represented by 

 the first three letters of their name, with the exception of the glucose radical, which is denoted by G. Furanose and 

 pyranose rings are indicated by / and p, respectively. The uronic acids are shown by the suffix A as in D-GpA which 

 indicates D-glucopyranuronic acid. 



(3) The Bromeae formed a natural tribe quite distinct from the 

 Brachypodieae, Festuceae, and Hordeae. 



(4) Two genera of the Festuceae, Lolium and Festuca, were 

 distinctive in containing an unusual trisaccharide. 



(5) Two genera of the Aveneae, Anthoxanthum and Holcus, 

 differed from the other two tested {Avena and Arrhena- 

 therum) in that they lacked yS-glucosan. According to the 

 authors the taxonomic positions Anthoxanthum and 

 Holcus are slightly suspect on morphological grounds, and 

 their contents of soluble carbohydrate show affinities with 

 the tribe Agrostideae and to a lesser extent with the 

 Phalarideae. 



With respect to the last statement, the biochemical data 

 applicable to the question of the relationship within the Aveneae lack 

 conviction. While over-all, the data appear to be suggestive, though 

 not conclusive, the rather small number of representatives of the 

 tribes sampled and the difficulty in appraising the biochemical 

 significance of the data raise doubts about their true phylo- 

 genetic significance. It is difficult to evaluate the significance of an 

 extra galactose unit on a trisaccharide with a terminal galactose or 

 the presence or absence of a soluble yS-glucosan. One is inclined to 

 suspect that the differences alone do not represent sound biochemical 

 criteria for adducing relationships at the tribal level and to predict 



