In botany, root refers to the part of a vascular plant, which typically lies underground. The major functions of roots are to anchor plants, and they absorb water and the dissolved minerals and help to carry them to other parts of the plant like the leaves and the stem. The roots differ significantly from the stem because they lack buds and leaf scars. Roots drive water and other dissolved minerals upwards through vessels known as xylem utilizing root pressure generated through osmotic pressure within the cells. This can be demonstrated when the stem of a plant is cut above the ground, and it exudes fluid. It is also believed that the force lifting the fluids is generated by transpiration and evaporation of water from the leaves and they are aided by the adhesive and cohesive forces of the molecules in the fluids and possibly with other factors, which all help to move fluids up the plant.
Growth Of Roots
Roots can only grow from the tip ends where they are covered by the root cap that resembles a thimble. The root cap is a protective cover that protects the growing tip as it makes its way in the soil. Beneath the root cap is a specialized tissue that is actively dividing known as the apical meristem. The newly produced cells are used for the growth of the root, particularly above the meristematic areas, and some are added to the root cap. Above the growth zone is the area of maturation, where most of the cell tissues mature and completes the process of cell differentiation, which starts at the upper part of the meristematic region. The root is made up of three parts and the outermost being the epidermis, followed by the cortex, and the innermost being the vascular cylinder.
Taproots are the main root systems that grow vertically to the ground. Most of the dicotyledons such as dandelions have taproots, and others like beets and carrots have taproots which are specialized for food storage. Taproots develop from the embryonic root known as radicle. They are deeply rooted below the surface and typically have a single main root, also known as the primary root, and they have secondary roots growing laterally from the main root. Taproot systems anchor the plants in the soil and help in absorbing water from deep below the surface, giving the plant a better chance to survive during drought.
Adventitious roots originate from another organ apart from the root, and it could be a stem or leaf. These roots are also found in underground stems as they appear in corn, rhizome, and tubers. Such plants could be vegetatively propagated through leaf or stem cutting. Occasionally, the roots pass through the air before reaching the soil, or they could remain suspended in the air. Adventitious roots are common in plants such as banyan, screw pine, and corn, among others. In other plants such as Tillandsia and orchids, the main means of attaching to non-soil surfaces is through the aerial roots, and they can attach to surfaces such as rocks and other plants.
The Difference In Where They Develop
Taproots are common in dicot plants where they develop from the radicle or the embryonic root, and they form the primary root of the plant. The tertiary and other lateral roots are visible. The adventitious or fibrous roots do not have the primary or the main root, but instead, all roots are similar, and they are found mostly in monocots plants. These roots emerge from the stem or even the leaves as opposed to the radicle.
Difference In Growth
Taproots have several features, and they grow deep-rooted below the surface of the soil, and it is long-lasting. Taproot is one long main root that is generally longer compared to other types of roots. On the other hand, fibrous roots are short-lived roots, and they are shallow. Adventitious roots can grow underground or aerial. They do not have a primary root, but instead, they have hair-like thin roots, and they grow together to form clusters, and as a result, there is no differentiation.
Difference In Existence
The plants which are characterized by the taproot system could survive in drought regions, and they help in anchoring the plant to the soil. The plants with fibrous roots or adventitious roots cannot survive in droughts, and therefore, they dry out so quickly. However, plants with adventitious roots are quick in absorbing surface water.
Difference In Appearance
Generally, plants with taproots have leaves that are characterized as having reticulate venation, while the plants with adventitious roots are characterized with leaves having parallel venation.
Similarities Between Taproot And Adventitious Roots
Both the adventitious and taproot systems are two types of roots found among the higher plants. The primary function of both roots is to absorb nutrients and water from the soil to be transported to other parts of the plant. The types of roots serve an important function of attaching the plant or anchoring the plant to the soil. All roots including both the adventitious and tap root can store food.