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In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. [1] The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation. [ 2 ]
In most seed plants, especially woody types, the endodermis is present in roots but not in stems. The endodermis helps regulate the movement of water, ions and hormones into and out of the vascular system. It may also store starch, be involved in perception of gravity and protect the plant against toxins moving into the vascular system.
Sclerenchyma is the tissue which makes the plant hard and stiff. Sclerenchyma is the supporting tissue in plants. Two types of sclerenchyma cells exist: fibers cellular 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.
The cells of the epidermis are structurally and functionally variable. Most plants have an epidermis that is a single cell layer thick. Some plants like Ficus elastica and Peperomia, which have a periclinal cellular division within the protoderm of the leaves, have an epidermis with multiple cell layers. Epidermal cells are tightly linked to ...
Outside the stele lies the endodermis, which is the innermost cell layer of the cortex. The concept of the stele was developed in the late 19th century by French botanists P. E. L. van Tieghem and H. Doultion as a model for understanding the relationship between the shoot and root, and for discussing the evolution of vascular plant morphology. [2]
In herbaceous plants, it occurs in the vascular bundles which are often arranged like beads on a necklace forming an interrupted ring inside the stem. In woody plants, it forms a cylinder of unspecialized meristem cells, as a continuous ring from which the new tissues are grown.
Traditionally, plant stem cells were thought to only exist in SAM and RAM and studies were conducted based on this assumption. However, recent studies have indicated that (pro)cambium also serves as a niche for plant stem cells: "Procambium cells fulfill the criteria for being stem cells since they have the capacity for long-term self renewal and being able to differentiate into one or more ...
A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves , flowers and fruits , transports water and dissolved substances between the roots and the shoots in the xylem and phloem , engages in photosynthesis, stores nutrients, and produces new living tissue. [ 1 ]