The cortex is well-developed and divided into two zones; a narrow outer layer of closely packed smaller parenchyma cells (exodermis) and a wide inner layer of larger open aerenchyma cells
The inmost area of the cortex is bounded by an endodermis or starch sheath with larger barrel shaped cells and thickened walls that mark the red staining casparian strip. Within the endodermis occasional small passage cells serve to transport of water into the stele or vascular bundle.
The stele is bound on its outmost edge by is a pericycle of single layered thin walled parenchyma cells.
The closed vascular bundles are arranged radially with arms of exarch xylem interspaced with patches of phloem and parenchymous conjunctive tissue. These tissues may become sclerenchymous in older roots
Vascular cambium is also absent, preventing secondary growth of the root.
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