266 



TEXTBOOK OF BOTANY 



Since an annual cylinder of wood is formed each year and the ends of 

 these cylinders seen in cross section appear as distinct rings of wood, 



Pericycle 



Phloem 



^Cambium 



^Xylem 



Vascular ray 

 Pith 



^// Epidermis and 



Fig 95. General regions and tissues of a stem of moonseed vine. Courtesy of 



World Book Co. 



the age of the stem may also be ascertained by counting the rings. An 

 annual cylinder of phloem is also formed each year, but the rmgs ot 



