Describe the internal structure of a dicot root.

(N/A) $\rightarrow$ To understand the tissue organization of roots,stems,and leaves,it is convenient to study the transverse sections of the mature zones of these organs.
$\rightarrow$ Internal structure of a mature dicot root (e.g.,sunflower): When a transverse section of a dicot root is stained and viewed under a microscope,the following regions are observed from outside to inside:
$(1)$ Epidermis $(2)$ Cortex $(3)$ Endodermis $(4)$ Pericycle $(5)$ Vascular bundles $(6)$ Pith.
$\rightarrow$ Epidermis: The outermost layer consisting of thin-walled cells. Many epidermal cells protrude to form unicellular root hairs,which help in the absorption of water and minerals.
$\rightarrow$ Cortex: Consists of several layers of thin-walled parenchyma cells with intercellular spaces.
$\rightarrow$ Endodermis: The innermost layer of the cortex,comprising barrel-shaped cells without intercellular spaces. The radial and tangential walls contain water-impermeable,waxy suberin deposits known as Casparian strips.
$\rightarrow$ Pericycle: Layers of thick-walled parenchyma cells located next to the endodermis. It is the site for the initiation of lateral roots and vascular cambium during secondary growth.
$\rightarrow$ Vascular Bundles: Xylem and phloem are arranged in an alternating manner. The number of xylem and phloem patches is usually two to four (diarch to tetrarch). Conjunctive tissue (parenchyma) lies between the xylem and phloem.
$\rightarrow$ Pith: The central part of the root,which is usually small or inconspicuous in dicot roots.