dast 



Fig. 55.— I. Transverse section of a vascular bundle of a sunflower 

 stem (enlarged about 120 diameters). Enlargement of X i^^ previous fig. 

 2. Longitudinal radial section through the same. / Medulla of stem ; 

 n the wood ; d the bast ; c the cambium of the bundle ; a spiral vessel ; 

 /"fibre ; pitted vessel ; s sieve tube ; t companion-cell ; b pericj'cle fibres; 

 € endodermis. 



