Veins are composed of xylem and phloem cells embedded in parenchyma, sometimes sclerenchyma, and surrounded by bundle sheath cells. The deficiency of SLL1, whose main function is to determine the development of the abaxial sclerenchyma cells of the leaf, leads to a defect in the formation of sclerenchyma cells on the abaxial side, thereby resulting in incurved leaves (Zhang et al., 2009). It may terminate short of one or both ends of the cell. In stem most usually it originates in the sub-pepidermal layer. The development of sclerenchyma cells is closely related to changes in leaf curling. Sclerenchyma cells with thick cells walls that are stained red due to lignin in the cell walls. Sclerenchyma is the supporting tissue in plants.Two types of sclerenchyma cells exist: fibers and sclereids.Their cell walls consist of cellulose, hemicellulose, and lignin.Sclerenchyma cells are the principal supporting cells in plant tissues that have ceased elongation. 2.2.3.1 Sclereids Figure 2.6.a. Sclereid cells or stone cells in the pear fruit. Sclerenchyma is a specialized tissue consisting of a group of cells in which secondary walls are often lignified. Ø The secondary cell wall is lignified and very hard. Sclerenchyma cells have lignified cell walls. Sclerenchyma cells are found wherever a plant needs strength and support, such as fibers, stone cells, wood, and water-conducting cells. Sclerenchyma cells have a lignified and strong secondary cell wall and are usually dead at maturity. They can be of two broad types: sclereids and fiber cells. In the center of the stem is ground tissue. 2.2.3 Sclerenchyma. There are two types of sclerenchyma cells: fibers and sclereids. In some fibers the secondary wall does not extend the full length of the cell lumen. Ø They have thick secondary cell wall. Ø Sclerenchyma is a simple permanent tissue in plants. Sclerenchyma fibers cap the vascular bundles. Figure 2.6.b. In some species, the first periderm appears rather deep in the stem, usually in the primary phloem viz., Berberis, and Vitis etc. The vein xylem transports water from the petiole throughout the lamina mesophyll, and the phloem transports sugars out of the leaf to the rest of the plant. The cells are nonstretchable and rigid. They are generally located in nongrowing areas of plant bodies, like mature stems or bark. Ø Sclerenchymatous cells are dead at their maturity. In plants, sclerenchyma is the supporting tissue that is composed of any of several types of woody cells. Ø Cells do not have protoplast when they completely developed. The term Sclerenchyma is derived from the Greek word ‘skleros’ means ‘hard’ and ‘enchyma’, an ‘infusion’. Sclerenchyma (Structure, Types and Functions of Sclerenchymatous Cells in Plants) What are Sclerenchymatous Cells? SCLERENCHYMA The cells making sclerenchyma tissue are rigid and function to support the weight of a plant organ. During ontogeny the primary-phloem fibers develop a thick primary wall over which a thick secondary wall is subsequently deposited. The term sclerenchyma was coined by Mettenius in 1805 and the cells are known as sclerenchymatous cells. Sclerenchyma is the tissue which makes the plant hard and stiff. Usually, mature sclerenchyma cells are dead cells that have highly thickened, lignified secondary walls. In (b) monocot stems, vascular bundles composed of xylem and phloem tissues are scattered throughout the ground tissue. Sclerenchyma tissues and conducting elements of the phloem and xylem were studied in stems in several stages of development. Sclerenchyma. The bundles are smaller than in the dicot stem, and distinct layers of xylem, phloem and sclerenchyma cannot be discerned. These cells tend to have thick, lignified secondary cell walls. They are dead at maturity. 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