The internal anatomy of root shows the following regions.
Epiblema or Piliferous Layer:
Single layered, compactly arranged cells, cuticle absent and provided with unicellular root hairs.
Cortex:
General Cortex is homogenously made of parenchyma. In old roots the epiblema dies off and the cells are suberised to form the exodermis. Innermost layer is the endodermis made of barrel-shaped cells with casparian thickenings. Endodermal cells opposite the protoxylem back the casparian thickenings and are called passage cells.
Stele:
Surrounded by a single-layered pericycle. Vascular bundles are limited in number i.e. diarch to search, usually tetrarch, radially arranged with exarch xylem and alternating patches of phloem and xylem. Conjunctive tissue lies between xylem and phloem which is parenchymatous. Pith is usually absent but if present small and parenchymatous.