FIBRO-VASCULAR BUNDLES. 



53 



in a collateral manner, that is, the phloem and xylem of 



Fig. lo. — A tranverse section of an open iibro-vascular bundle in the stem 

 of the sun-flower. M, pith ; X, xylem ; C, phloem ; E, cortex ; s, small, 

 y, large spiral vessels ; t, pitted vessels ; i', pitted vessels in course of 

 formation ; h, wood-fibres ; st, sieve-tubes ; b, bast-fibres ; e, bundle- 

 sheath ; ic, inter-fascicular cambium. B, radial vertical section through 

 a similar bundle (somewhat simplified) lettered as in the transverse 

 section (highly mag.). (From Prantl. ) 



