69 



3. The Root 



Is protected by a cay many cells thick. Beliind 

 the cap is the root-hair region. As has been 

 already stated, the roots arise from the leaf bases, 

 [n transverse section a young root presents the 

 following structure : — 



(a) PiLiFERY. This is one cell thick, and produces 

 the root hairs. T'he root hairs are absorptive, 

 their outer walls becoming mucilaginous they 

 adhere closely to the particles of soil. 



(b) Cortex. The outer part of this tissue is thin- 

 walled and the inner thick-walled. 



(c) The Endodermis is similar in most respects 

 to the endodermis found in the stem, the only 

 difference bsing that one endodermis surrounds 

 the whole vascular cylinder in the root, while in 

 the stem evenj bundle has its own endodermis. 



(d) The Pericycle is as a rule double, and like 

 the endodermis encloses the whole vascular 

 cylinder. 



(e) The "Vascular Cylinder consists of two 

 phloem groups opposite each other, and two 

 xylem groups opposite each other and alternate 

 with the phloem groups. There are thus four 

 distinct groups of vascular tissue arranged thus : 



Bast 

 Wood Wood 



Bast 



