It is the first root to appear from the seed and remains the largest, central root of the plant. Lateral roots will branch off from the taproot and then smaller lateral roots will form from the initial lateral roots, but the central taproot will remain the largest and will burrow down into the soil the deepest. The branching of lateral roots serves to increase the surface area for water and mineral absorption. Taproots are generally found in dicots i. They generally grow more deeply into the soil, it often become a modified storage organ for food reserves such as carbohydrates.
The food reserves can be drawn upon to ensure good development of flower stalk and seeds. Taproots anchor plants deeply, helping to prevent the wind from blowing them over and stabilizing plants that grow in areas of shifting soils such as beaches or sand dunes.
Plants with taproot system include:. The root system is generally shallower than the taproot system and forms a dense network of roots. Fibrous roots systems help prevent soil erosion as they anchor plants to the top layer of soil. Some plants have a combination of both taproots and fibrous roots.
Plants that grow in dry areas often have deep root systems whereas plants growing in areas with abundant water are likely to have shallower root systems. Viva Differences. Taproot is the thickest while secondary and tertiary taproots have a much reduced thickness. After germination of a seed, the first root that emerges from it is known as radical or primary root. The radical eventually forms the taproot. The fibrous root system begin as a taproot from the radicle, but as the plant grows, the radicle degenerates and no primary root is seen.
Onions, tomatoes, lettuce grasses, lilies, palms, corn, beans, peas, sweat potatoes, rice and wheat. Cell division occurs in the apical meristem. Root growth begins with seed germination. When the plant embryo emerges from the seed, the radicle of the embryo forms the root system. The tip of the root is protected by the root cap , a structure exclusive to roots and unlike any other plant structure. The root cap is continuously replaced because it gets damaged easily as the root pushes through soil.
The root tip can be divided into three zones: a zone of cell division, a zone of elongation, and a zone of maturation and differentiation Figure 2. The zone of cell division is closest to the root tip; it is made up of the actively dividing cells of the root meristem. The zone of elongation is where the newly formed cells increase in length, thereby lengthening the root.
Beginning at the first root hair is the zone of cell maturation where the root cells begin to differentiate into special cell types. All three zones are in the first centimeter or so of the root tip. The root has an outer layer of cells called the epidermis, which surrounds areas of ground tissue and vascular tissue.
The epidermis provides protection and helps in absorption. Root hairs , which are extensions of root epidermal cells, increase the surface area of the root, greatly contributing to the absorption of water and minerals. Figure 3. Staining reveals different cell types in this light micrograph of a wheat Triticum root cross section. Sclerenchyma cells of the exodermis and xylem cells stain red, and phloem cells stain blue. Other cell types stain black. The stele, or vascular tissue, is the area inside endodermis indicated by a green ring.
Root hairs are visible outside the epidermis. Inside the root, the ground tissue forms two regions: the cortex and the pith Figure 3. Compared to stems, roots have lots of cortex and little pith. Both regions include cells that store photosynthetic products. The cortex is between the epidermis and the vascular tissue, whereas the pith lies between the vascular tissue and the center of the root. The vascular tissue in the root is arranged in the inner portion of the root, which is called the stele Figure 4.
A layer of cells known as the endodermis separates the stele from the ground tissue in the outer portion of the root. A waxy substance called suberin is present on the walls of the endodermal cells. This waxy region, known as the Casparian strip , forces water and solutes to cross the plasma membranes of endodermal cells instead of slipping between the cells.
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