How Many Types Of Elements Together Make Up The Xylem Tissue Name Them?

Four different types of components together make up the xylem tissue. Tracheids, vessels, xylem parenchyma, and xylem fibres are among these components. Xylem, together with the phloem, is a transport tissue that is present in vascular plants. Transporting water and nutrients from the roots to the leaves and stems, as well as acting as support, is the crucial job of the xylem. Carl Nageli coined the term "Xylem" in 1858.

Types of Xylem

There are two main types of xylem: primary and secondary.

Both have the same function, but are categorised by growth type-

Primary xylem: It is formed by the initial growth of the plant. This growth can be seen on the stem, root and tip of the flower bud. This makes the plant taller and has long roots. This is known as early growth because it occurs at the beginning of the growing season.

Secondary xylem: It is formed from the secondary growth of the plant, which allows the plant to expand over time. For example, a wide tree trunk with lots of secondary growth. Occurs annually after initial growth. The secondary xylem is responsible for the dark rings on the tree trunk that are used to determine the age of the tree.

Components of Xylem

Xylem is mostly made up of four different types of cells, some of which are living and some of which are dead.

1. Tracheids: These are the basic xylem cells; they have an extended, tube-like form with a tapered end. Pits puncture a significant amount of the tracheid's cell wall. In tracheids, secondary thickening can take numerous forms, including annular thickening, helical spiral thickening, ladder-like scalariform thickening, pitted thickening, and reticulate thickening.

2. Vessels: They are also called trachea and are the second group of xylem elements that consist of short and tubular cells. Vascular components are vessel segments or vessel elements.

3. Xylem fibre: Dead cells with lignified walls and a central lumen. Xylem fibres help in water transport and mechanical support.

4. Xylem parenchyma: They are nothing more than living cells that store starch and fat. It is also useful for transporting water over short distances. You can see all the components in the xylem diagram.

Xylem Structure and Function

Xylem Structure-

Xylem is made up of various cell kinds. Tracheids are one of them; their lengthy cells aid in the transportation of xylem sap and offer structural support. Another is the vessel component, which although smaller than the tracheids aids in water conduction. All of the vessel elements are connected by perforated plates to form one continuous vessel. Additionally, it has xylem parenchyma, which produces the plant's softest tissue as well as lengthy fibres that help sustain the plant. When observed under a microscope, the xylem has a star-like appearance. The answer is essentially the same for the xylem structure.

Xylem function-

The most important function of the xylem is to transfer water and nutrients, including mineral and inorganic substances, from the root of the plant to other parts of the plant. The substance that flows in the xylem cells is called xylem sap. The matter is transported by passive transport and does not require external energy. The phenomenon that xylem sap flows upwards against gravity is called capillary action due to liquid surface tension.

Plants absorb carbon dioxide from the atmosphere and water from the soil. When the leaf stomata open and absorb carbon dioxide, the leaves evaporate a large amount of water. In this way, xylem is necessary to carry water in the place of photosynthesis and in other parts of the plant.

Characteristics Of Xylem Parenchyma

The main characteristics of the xylem are:

• They are the only living xylem cells.

• It is always thin and consists of cellulose, the cell wall of the xylem parenchyma.

• It contains prominent protoplasm and a nucleus.

• They have large vacuoles and the cell walls are colourless.

• Viable parenchymal cells are present in both primary and secondary xylem.

• Fat and protein, components of parenchymal cells, change with the seasons.

• They consist of crystals containing parenchymal cells with lignified walls and possibly divided septa.

• Chloroplasts, present in angiosperms, woody plants, and grasses, form the xylem parenchyma.

• Tylose is a blood vessel from the lateral growth of axial and linear parenchymal cells.

• Store various substances that can cause tylose.

• Sclereids may be differentiated into tyloses.

• Cells migrate toward tylose in the nucleus and cytoplasm.

• Which parenchymal cells that give rise to tyloses are called contact cells.