Roots are cylindrical, non-green parts of the plant that grow underground. It does not have any nodes, leaves, or buds, but it does have endogenous lateral branches. The roots are always growing in the pull of gravity (geotropism) and distant from the direction of the sun (phototropism) (phototropism). As a result, the roots are referred to as positively geotropic and negatively phototropic, respectively. Roots are usually formed from the radical part of the developing embryo in most cases.
The fibrous root is a type of plant in which the primary roots degenerate and the fibre-like roots emerge from the lower base of the stem. It is found in monocots and is characterised by the presence of fiber-like roots. The epidermis of the root is followed by the cortex, endodermis, pericycle, vascular bundle, and pith in the anatomical order. Conjunctive tissue can be found between the xylem and the phloem in the root’s radial vascular bundle.
Root of the Dicotyledon
A dicot root does indeed have a tap root system, and the tissues in its root show the following arrangement:
- The epidermis, also known as the Epiblema, is the outermost layer of the root. It is usually only one layer thick. Root hairs, which are unicellular tubular extensions of the epidermis that aid in the absorption of water and minerals from the soil, are found on the outer wall of the epidermis.
- b. Cortex: Parenchymatous cells can be found in several layers throughout the body, from the epidermis to the endodermis, and these layers are referred to as the cortex. Cells in the cortex are thin-walled and loosely packed in order to allow for the unrestricted movement of water through the cells.
- Endodermis: The endodermis is the cortex’s innermost layer, and it is located between both the cortex and the stele region of the brain. It is formed by a single layer of barrel-shaped cells with a special thickening of waxy suberin in the radial and tangential walls, known as the casparian strip, that are arranged in a spiral pattern. The casparian strip is impenetrable to water molecules because of its structure.
- d) close proximity to the epidermis is the pericycle, which is composed of a thick-walled parenchymatous cell with a thin membrane. It can range from a single layer to several layers in thickness. It is critical in the development of secondary growth in dicot root systems.
- Radial Vascular Bundle: Because the xylem and the phloem are located at different radii, a radial vascular bundle is formed. The xylem that is present is in exarch condition, with metaxylem located in the centre and protoxylem located towards the periphery of the structure.
- Conjunctive tissue: Between the xylem and the phloem, parenchymatous cells are present, and this tissue is referred to as conjunctive tissue, and it aids in the development of the root’s secondary growth.
- Pith: It is found in the centre of the flower. It is composed of a parenchymatous cell with intercellular spaces between the cells. The pith in the roots of dicots is not well developed; it is slight and inconspicuous in their roots.
Root of the Monocotyledon
There are some minor differences between the anatomy of roots and that of a dicot root, but the two are quite similar. The following is an explanation of the tissue organisation of the root:
- in the root’s epidermis, which is the outermost layer, there are a large number of unicellular root hairs, which serve as a protective layer.
- cortex:- A loosely arranged cortical structure composed of parenchymatous cells is known as the cortex. The hypodermis has been removed.
- Pericycle: In monocots, the pericycle is an enduring layer that only gives rise to lateral roots because the cambium is absent.
- Radial Vascular Bundle: The radial vascular bundle is the type of bundle that has been described. Since there is no vascular cambium present in the vascular bundle, the vascular bundle is sealed and does not exhibit secondary growth.
- Conjunctive Tissue: The conjunctive tissue is made up of parenchymatous cells that are found between the xylem and the phloem.
- Pith: The pith of the monocot plant is large and well formed in the roots of the plant.
Conclusion
Roots are the basement parts of plants that are favourably geotropic and adversely phototropic in their orientation. The primary function of the root is to absorb water and minerals from the surrounding environment through root hairs. Roots typically have such a single-layered epithelium with a single celled tubular extension known as root hairs that extends from the epidermis. Following the epidermis, we have multifaceted cortex cells composed of parenchymatous cells, which are located beneath the dermis. The endodermis, which is a barrel-shaped structure at the end of the cortex cells, has a waxy covering that prevents water from flowing through it. Unlike the monocot root, the dicot root contains the Casparian strip, which is not present in the monocot root. Roots have a radial vascular bundle, which ranges from diarch to hexarch in dicot roots and from polyarch to hexarch in monocot roots, depending on the species. They have a collenchyma cell called pith in the centre of the root, which is narrow and inconspicuous in dicot roots but large and well established in monocot roots, which is present in both.