3X4 THE STRUCTURE OF ECONOMIC PLANTS 



bach (i8) that this radial enlargement may result in a marked 

 shortening of the hypocotyl. 



According to Winter (36), the polar protoxylem elements, 



Fig. 164. A, triarch root of alfalfa showing lateral root formation; B, tetrarch stage; 

 C, D, E, bifurcation of metaxylem and formation of pith ; F, cotyledonary node below point 

 of divergence of cotyledons; G, transection of cotyledons and epicotyl; H, triad bundle of 

 cotyledon; cot, cotyledonary plane; int, intercotyledonary plane; a, h, c, bundles of first 

 foliage leaf; d, median bundle of second foliage leaf. (After Winter.) 



