STEM STRUCTURE 183 



RHIZOMES 



The characters and arrangements of tissues in 

 underground stems or rhizomes correspond closely 

 to those of overground stems. Monocotyledonous 

 rhizomes retain the primary structures through life 

 while those of the dicotyledonous class undergo the 

 changes incidental to the formation of secondary 

 tissues. Rhizomes showing primary structure are 

 readily distinguished from roots by the presence of 

 nodes or joints, and by the absence of root hairs. 

 They are further distinguished from roots by the 

 possession of complete fibro-vascular bundles even 

 in the earlier stages of growth. 



