xvi] 



ROOT ANATOMY 



209 



r 



FIG. 138. Callitriche 

 stagnalis, Scop. T.S. 

 central cylinder of ad- 

 ventitious root of water 

 form ( x 470) ; s, sieve 

 tube. [Schenck, H. 

 (1886).] 



FIG. 139. Vallisneria spiralis, L. A, T.S. adventitious root 



(x 240). B, T.S. central cylinder (x 470); end, endodermis, 



s, sieve tubes of which three are present. The central vessel 



is unthickened. [Schenck, H. (1886).] 



FIG. 140. T.S. central region of roots of Naias-, sieve tubes shaded. A, Naias 



major, All., two central vessels. B and C, N. minor, All., one central vessel in B 



and two in Q. [Sauvageau, C. 



