THE STEM 129 


a : 
SUMMARY OF PRINCIPAL TISSUES IN A DICOTYLEDONOUS STEM 
Epidermis 
Epidermal cells 
Guard cells 
Trichomes 
Cortex 
Collenchyma 
Parenchyma 
Starch sheath 
Stele 
Pericycle 
Parenchyma 
Sclerenchyma 
Pith rays 
Parenchyma 
Pith 
Parenchyma 
Vascular bundles 
Phloém 
Sieve tubes 
Companion cells 
Phloém parenchyma 
Cambium 
Meristematic cells 
Xylem 
Tracheary cells 
Vessels Spiral 
and Annular 
Tracheids | Pitted 
Wood fibers 
Wood parenchyma 
ANATOMY OF MONOCOTYLEDONOUS STEMS 
Monocotyledonous stems are similar to dicotyledonous stems 
in having an epidermis, a cortex, and a stele. The cortex may 
be well developed and sharply marked off from the stele, or it 
may be very narrow and inconspicuous (Fig. 125). It is in 
