30 



Elementary Botany 



made up of permanent tissue, consisting principally of a mass 

 of parenchymatous cells forming the ground tissue, and in this 

 there are developed, more or less completely, bundles of pros- 

 enchymatous cells and vessels, forming what are Jcnown as 

 fibro-vascular bundles, running from the base of the root 

 towards the apex. 



These bundles consist of xylem and phloem, very similar 

 to that which exists in the stem (see Qiapter VI.). Each 



Fig, so. — Transverse section of root of Phaseolus, m, pith ; j, endodermis or sheath of 

 fibro-vascular bundles, with parenchyma of the ground tissue externally ; pc, peri- 

 cambium layer : b, primary phloem of bast fibres ; g^ primary xylem, with vessels ; 

 c, cambium. (After Sachs.) 



bundle contains prosenchymatous cells or fibres, vessels and 

 parenchyma, but they differ from the bundles of the stem and 

 leaves, in that the vessels are, as a rule, first formed near the 

 circumference of the bundle, and the xylem and phloem masses 

 (which vary in number in different plants) alternate instead of 

 being placed the one outside the other. The bundles thus 

 form an irregular star of three, four, or six rays. 



