Internal structure of Monocotyledonous Root (Maize) : Maize is a dicot plant. While taking section of maize root under microscope following three layers are seen clearly, (1) Epidermis (2) Cortex (3) Stele.
Epidermis : This is the outermost protective layer of root. From the cells of this layer thin walled tube like appendages are produced. They are called root hairs. The cells of this layer do not possess cuticle layer because its function is to absorb water and salts from the soil.
Cortex : In cortex, outer cortex, inner cortex and endodermis are included.
(i) Exodermis: This layer is located immediately below epidermis. Its cells are large, suberised thick walls. It protects inside tissues due to loss of epidermis.
(ii) Hypodermis : A region of 3-4 layers located below exodermis is called hypodermis. The wall of cells of these of these layers is lignified and becomes strong. This region is made up of collenchyma.
(iii) Inner Cortex : The region located inside the cortex is called inner cortex. This region is made up of parenchyma cells. They have thin wall and are round in shape.
(iv) Endodermis : The innermost layer of cortex is called Endodermis. The cells of this layer are connected tightly with each other. The radial wall and inner wall is stained with lignin and suberin. This stain appears like horizontal .C.. Some of the cells in this layer stay with stain. They are called passage cells. These cells are exactly opposite to protoxylem and alive.
Stele: In stele pericycle vascular, bundle, conjunctive tissues and pith are included.
The number of group of xylem and phloem tissue is more than 8. So such stele s called polyarch.
(i) Pericycle : Pericycle is a one layered covering located inside of endodermis. The cells of this layer are alive, thin walled and parenchymatic.
Lateral roots produced by cells of this layer are located opposite to protoxylem. Thus they originate of their own.
(ii) Vascular Bundles : Here Vascular Bundles are of radial type. The Vascular Bundles of xylem and phloem are arranged at different radii. The development of xylem is exoarch as protoxylem are outside while metaxylem are located inside.
Phloem tissue is made up of sieve tube and companion cells which seem as small group between protoxylem.
(iii) Conjuctive Tissue : The tissue connecting xylem and phloem and having location with pericycle and pith is known as conjuctive tissue. Initially they are made up of parenchyma. Later on they become of collenchyma.
(iv) Pith: The cells of pith are parenchymatic and they are more in number,
Inter cellular spaces can be seem between cells.
