EXPERIMENTAL MATERIALS AND METHODS 



15 



i-«- 



Phloem 



580 a- 



Root hair zone 



■ "I'niniiniiiiiiiiiiiiiiiiiiiiiiiiiii 



iZone of most rapid 

 I elongation 



■< — ■ 260/u >J 



Zone of most rapid 

 cell division 



Root cap 



Xylem Piliferous layer 



En do derm is 



Immature 

 xylem 



iVloture phloem 

 elements 



stem 

 Immature phloem 

 elements 



(a) 



Pericycle 



Protophloem IVletaxylem 



Piliferous layer 



Stele 



Root hair ce 



asparian band 



(b) 



Fig. 3. Root Anatomy. 



a. Diagram of a tobacco root tip showing the spatial relations of different 



tissues and order of maturation (redrawn from Esau, 1953); b. Transverse 



section of a root (after Priestley, 1920) 



