(i) Epidermis: The outer layer of rachis is called epidermis or epidermis. It is unilayered and composed of parenchyma cells.
(ii) Hypodermis: The inner layer of epidermis is called hypodermis or hypodermis. It is composed of sclerenchyma cells.
(iii) Cortex: The inner layer of hypodermis is called cortex. It is multi-layered. The cortex consists of horse-shaped styli or vascular bundles. Its vascular bundles are hydrocentric i.e. xylem in the center and phloem around it.