CARBOHYDRATES 141 



culture and with C^^ labelled sugar alcohols. One could utilize liquid 

 root-culture techniques or measure callus development from cotyledon 

 explants upon agar with sugar alcohols as the carbohydrate source. 



Inositol and related cyclic alcohols 



This group of substances is arbitrarily discussed along with 

 the other sugar alcohols. Empirically, they are close to the sugar 

 alcohols but biosynthetic pathways leading to the synthesis of cyclic 

 alcohols may be quite different. 



The best known of the cyclic alcohols is the widely distributed 

 inositol. Meso-inositol occurs in numerous higher plants while other 

 isomers are more hmited in distribution. 



H /OH H0\ OH 

 Ho\oH hAh 



OH 



meso-inositol 



Two monomethyl ethers of inositol, bornesitol and sequoyitol, 

 occur in several families. Another monomethyl ether, pinitol, is found 

 among a variety of conifers, in Ephedra, and also among a number of 

 angiosperm families (for example, Leguminosae). Dambonitol, a 

 dimethyl ether, occurs in a number of species of angiosperms, and the 

 deoxyinositol, quercitol, is found in a number of angiosperm families. 



The cyclitols, pinitol and quercitol, have been investigated 

 from a systematic orientation (Dangschat, 1958; Plouvier, 1955). 

 Despite the fact that they occur among numerous unrelated groups, 

 within certain taxonomic groups the distribution of these compounds 

 is definitely meaningful. 



Quercitol is found in a number of families of both monocots 

 and dicots. However Plouvier, who studied the distribution of quercitol, 

 found that quercitol generally occurred only in one or a few represen- 

 tatives of a family; that is, it did not appear to be particularly charac- 

 teristic of the family. In the family, Fagaceae, the compound was 

 described from the genus Quercus, but Plouvier found that several 

 species of Fagus and Castanea, of this family lacked quercitol. How- 

 ever, all of thirty-three species of Quercus investigated contained 

 quercitol. 



Thus, quercitol appears as a genus-specific character in 



