Xylem is the type of the transport tissue present in the vascular plants, the vascular plants contain two types of the transport tissue they are xylem and phloem. The xylem tissue is known is a better ways as wood, which is present throughout the plant. The xylem transports water and the minerals throughout the plant from its root and provides support to the plant. The important cells present in xylem are called xylem vessels, which is very long and narrow. These are the dead cells and they do not have a cross walls, these cells are arranged in the columns to form a tubes which are long from where is water is drawn.
The transpiration process occurs when the water is evaporated from the leaves then by the process of osmosis the water are drawn across the leaf to replace it by drawing the water out from the xylem. This process will create the pressure in the xylem vessels and the sidewalls become strong and unbreakable with the help of rings of the lignin, this is the rigid substance, which protects from collapsing, the xylem provides a mechanical support to the plant. Through the tiny holes of the xylem vessels the water cross from the one tube to the another tube. In particular age of trees, the xylem is blocked and to replace the old xylem the new one is formed outside the trunk. The dead xylem will remain in the plant and gives a support for the plant.
Functions of xylem
- Xylem is the important tissue present in the vascular plants, which is responsible for transporting the water and the other nutrients from soil to leaves and stems.
- Xylem plays an important role in supporting and strengthening the tissues and organs and maintains plant architecture and resistance to bending.
- The mature xylem, which transports the water to all parts of plants when they are dead the transporting of water, becomes the passive process with the tiny active root pressure component.
- The xylem grows by dividing and differentiating the cells of the bifacial lateral meristem in most of the woody plant, the vascular cambium produces the secondary xylem and the phloem.
- Xylem is otherwise called as wood and it is one of the valuable renewable resources in the world.
- The chemical, biological and physical properties of the xylem cell are determined by the frequency, morphology and distribution and by resulting the properties of the wood.
- The physical and the chemical properties of the wood determines the role of the carbon cycle through its storage capacity of carbon and gives resistance to decay when it is dead or alive also in the various sediments.
- The physical and the chemical properties of the wood are determined by the composition and the interaction of polymers called cellulose, lignin and hemicelluloses.
- Depending up on the expression of the regulatory genes the woody and the herbaceous plants differ and control the quantity and duration of formation of xylem.