A thin transverse section of young monocot stem shows the following parts: Epidermis, ground tissue and vascular tissue.
Epidermis: it is the outermost protective layer .Itconsists of single row of cells which are rectangular and closely arranged. The outer wall of epidermal cells is coated with cuticle. It prevents the loss of water.Trichomes are absent. Epidermis may have a few stomata .Epidermis may have a few stomata here and there. Epidermis protects the internal parts of the stem.
Ground tissue: The undifferentiated mass of cells inside the epidermis except the vascular bundles is called ground tissue. The region just below the epidermis is called thehypodermis. In monocot stem the hypodermis is scelrenchymatous.It consist of 2 or 3 layers of cells in the ground tissue just below the epidermis. Theremaining inner part of the ground tissue is parenchymatous with intercellular spaces. There is no differentiation into cortex, endodermis, pericycle, medullary ray and pith.
Vascular tissue: Vascular bundles are numerous and scattered inthe ground tissue. The vascular bundles lie closer near the periphery than at the centre. The peripheral bundles are smaller than the inner bundles. Xylem and phloem are arranged on the same radius and are called collateral. The cambium is absent and is said to be closed bundle. The xylem is composed of tracheid vessels, xylem fibers and xylem parenchyma. The protoxylem is facing the center while the metaxlem is away from the center and is called endarchxylem. The phloem is composed of sieve tube members and companion cells. The phloem fibers and phloem parenchyma are absent. Each vascular bundle is enclosed in a bundle sheath. It is made up of sclerenchyma.