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. 
ha 
p m t en 
Fig. 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 (t), 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: 
1. Epidermis with cutinized outer walls, the cells often elongating 
to form root-hairs. 
