Importance of Vascular Tissue in Plants

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Vascular tissues are vital and specialised components of vascular plants. It should be noted that not all plants have vascular tissues; this is because these specialized cells are used for extensive transportation of various substances in plants and some plants do not need such components as there are no conveyance of much materials. Woody plants like trees and non-woody plants such as flowers have vascular system of transportation of substances. Plants like Liverworts, hornworts and mosses do not have vascular tissues, so they are called non-vascular plants because of the lack of the elaborate transportation system.

The vascular tissue system of a typical plant is composed of the xylem, phloem, cork cambium and vascular cambium. Cork cambium and vascular cambium are referred to as meristems while xylem and phloem are the tissues that that transport fluid and nutrient in the plants. The transportation of these substances is either from the leaf to the other parts of the plants or right from the root to the leaf.

The long cylindrical shape of xylem and phloem which comes in form of pipes validates their function of transporting minerals and water through the plant system. The positioning of the xylem and phloem is dependent on their location in the plant. The xylem characteristically lies closer to the interior of the stem with phloem towards the peripheral of the stem in stems and roots. While in the leaf, the xylem is slanted towards the adaxial surface of the leaf and phloem is oriented toward the abaxial surface of the leaf. The vascular cambium earlier mentioned comes in between the xylem and the phloem. This meristem produces cells that increase the thickness of the plant and not the length thereby enabling the plants to be stouter. The cambium corks, on the other hand, are located between the phloem and most prevalent in woody plants. They produce solidified cork cells that protect the surface of the plant and lessen water loss.

The phloem and the xylem have three basic functions that they perform in the plants, namely, transportation of water, food transportation and communication, physical support for the plant.  Leaves lose a lot of water through the process of transpiration, which serves to cool the entire system of the plant. This transportation of water from the root through the stem to the leaf is by a capillary movement through the xylem. The phloem is more concerned with the transportation of food materials such as simple sugar made by the leaf through the process of photosynthesis. This downward movement of food substances called sap (thick solution of sucrose and other nutrients) through the phloem is necessary since other parts of the plant do not produce food.

The xylem offers mechanical support to the plant through lignin which is a tough fibre formed from the stiffened dead tubular cells. These dead xylem cells may no longer be transporting water, but now offer support to the plants.

More about this author: Oluwasegun P. Gbolagun

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