PLANT ORGANS AND ORGANISMS 



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Dicotyledons. The typical dicotyl root is a tetrarch one, four 

 xylem alternating with four phloem patches. These roots have an 

 unlimited power of growth. 



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p m t en 



PIG. 59. Part of a transverse section of Honduras sarsaparilla root showing 

 epidermis (e), root hair (ha), hypodermis (h), cortex (c), rendodemis (en), peri- 

 cambium (p), trachea of one of the numerous xylem patches (/), and pith (m). 

 The phloem patches are the small oval cellular areas wedged in between the outer 

 portions of adjacent xylem masses. (Photomicrograph.) 



A. Of Primary Growth. 



A transverse section of a dicotyl root in its young growth shows 

 the following structure from periphery toward center: 



i. Epidermis with cutinized outer walls, the cells often elongating 

 to form root-hairs. 



