54 



PLANT GROWTH 



and have the woody region in a more or less heavy cyHnder 

 between the pith and the bark. The buds are usually more 

 conspicuous on this type of stem than on the monocotyledo- 

 nous stems. 



Transverse 

 View 



Transverse View 



— epidermis 

 — phloem ray 



xylem (wood) ray 



cambium 



phloem 



fibers 

 — -primary 

 xylem 



secondary 

 ""xylem 



— cortex 



\cQrtex pi 

 ^epidermis 

 wood ray cells 



yessels 



spiral--''' 

 _scalariform- 



Radial View 



phloem cortex 



xylem \ 



cambium 

 Tangential Vietv 



Fig. 12. Semidiagrammatic representation of a one-year-old stem of tulip-tree, in 

 transverse, radial, and tangential views to show the relative size and shape of the many 

 kinds of cells. (From Hill, Overholts and Popp's Botany, McGraw-Hill Book Co., 

 1936.) 



The main tissues of the stem correspond with those of 

 like functions in the roots. The central region is the pith, 

 usually absent in roots. In young, and in herbaceous stems 



