Dicot roots have vital anatomical structures such as pith, epiblema, pericycle, vascular bundles, cortex and endodermis. Here, let’s learn about the primary structure of the dicot root in detail.
Table of Contents
Epiblema
It is the root’s outermost cell layer. It is composed of thin-walled, flattened and slightly elongated parenchymatous cells that are tightly packed together. The absence of a distinct cuticle and stomata distinguishes the epidermis of the root from that of the stem.
Trichoblasts, also known as root hairs, are thin-walled tubular outgrowths produced by certain epiblema cells. Trichoblasts are often smaller than other epidermis cells. The epiblema is also known as a piliferous layer because it has root hairs (pilus-hairs).
Water and salts from the soil are absorbed by the root hairs and thin-walled epidermal cells. Typically, root hairs don’t survive for more than a week. The epidermal cells undergo suberization and cutinization upon death.
Cortex
It is located beneath the epiblema. The cortex is made up of several layers of parenchyma cells with thin-walled cells. The parenchyma cells might be angular or round. They enclose intercellular gaps where gases can diffuse. Food is stored in the cells of the cortex. Additionally, they transport water from the epidermis to the interior tissues.
Endodermis
Typically, endodermis is regarded as the cortex’s deepest layer. It consists of a single layer of barrel-shaped cells that do not encapsulate intercellular gaps. Along their tangential and radial walls, the immature endodermal cells have a band of thickening known as a Casparian strip. It functions as a checkpoint to stop fluids from moving between the cortex and phloem and to stop plasmolysis. There are some endodermal cells close to the protoxylem that lack Casparian strips and are referred to as transfusion cells or passage cells. Water and minerals can diffuse radially through the endodermis because of these cells.
Pericycle
The endodermis is often followed by the pericycle. The pericycle is a vital layer which typically indicates the outer boundary of the vascular strand. In the early root, the pericycle cells have thin walls and are parenchymatous. It contributes to the formation of the vascular cambium. It is where the cork cambium also grows.
The pericycle serves as the genesis of all lateral roots. Some aquatic and parasitic plants lack a pericycle in their roots.
Explore: Preparation and Study of T.S. of Monocot and Dicot Roots and Stems
Vascular Strand
The vascular bundles are radial and are typically found inner to the pericycle. Tracheids, vessels, xylem parenchyma and xylem fibres make up the exarch xylem, which is a protoxylem at the periphery and a metaxylem at the centre.
Under the pericycle, the phloem produces oval masses that alternate with xylem bundles. Sieve tubes, companion cells, and phloem parenchyma make up phloem. Phloem fibres are typically missing or diminished. Conjunctive or complementary tissue made of parenchymatous cells is what separates the xylem and phloem bundles from one another.
Pith
Pith often doesn’t exist in dicot root. Even if present, it is quite small or feebly developed and is made up of parenchymatous cells. There are no intercellular spaces. Both food and waste products are both stored in these cells.
Keep exploring BYJU’S Biology to learn more such exciting topics.
See More:
- Difference between Monocot and Dicot Stem
- Difference between Dicot and Monocot Root
- Monocot and Dicot Plants Anatomy
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