70 



STRUCTURE OF THE STEM 



84. Comparison of the monocotyledonous and the dicotyledo- 

 nous stem. 1 



General 

 Structure : 



Structure of 

 Bundles : 



MONOCOTYLEDONOUS 

 STEM 



A hard rind of rather 

 uniform structure. 

 Bundles intermixed 

 with the pith. 



Bundles dosed ; that 

 is, without permanent 

 cambium. 



DICOTYLEDONOUS 

 STEM 



A complex bark , usually 

 on young shoots, consist- 

 ing of an epidermis, a 

 corky layer, a green layer, 

 and a layer of bast. A 

 layer of cambium. Wood 

 in annual rings. Pith in 

 a cylinder at the center. 



Bundles open, with per- 

 manent cambium. 



Growth in 

 Thickness : 



Cells of mature parts 

 of stem expand some- 

 what, but (in most 

 palms) new ones are 

 not formed. 



Nerw wood cells formed 

 throughout growing sea- 

 son from cambium ring. 



1 This comparison applies only to most of the woody or tree-like stems. 



