Search results
Results from the WOW.Com Content Network
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 ]
Parenchyma is a versatile ground tissue that generally constitutes the "filler" tissue in soft parts of plants. It forms, among other things, the cortex (outer region) and pith (central region) of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, and the endosperm of seeds.
The endodermis is the boundary between the cortex and the stele. In many seedless plants, such as ferns, the endodermis is a distinct layer of cells immediately outside the vascular cylinder (stele) in roots and shoots. In most seed plants, especially woody types, the endodermis is present in roots but not in stems.
In a vascular plant, the stele is the central part of the root or stem [1] containing the tissues derived from the procambium. These include vascular tissue, in some cases ground tissue and a pericycle, which, if present, defines the outermost boundary of the stele.
Bark tissues make up by weight between 10 and 20% of woody vascular plants and consists of various biopolymers, tannins, lignin, suberin and polysaccharides. [35] Up to 40% of the bark tissue is made of lignin, which forms an important part of a plant, providing structural support by crosslinking between different polysaccharides, such as ...
[2] [5] The Casparian strip is a band of hydrophobic, corky-like tissue that is found on the outside of the endodermis and the exodermis. Its main function is to prevent solution backflow into the cortex and to maintain root pressure. [6] It is also involved in ensuring that soil is not pulled directly into the root system during nutrient ...
Most or all ground tissue may be lost in woody stems. Vascular tissue, consisting of xylem, phloem and cambium; provides long distance transport of water, minerals and metabolites (sugars, amino acids); whilst aiding structural support and growth. The arrangement of the vascular tissues varies widely among plant species. [8]
The epidermal cells of aerial organs arise from the superficial layer of cells known as the tunica (L1 and L2 layers) that covers the plant shoot apex, [19] whereas the cortex and vascular tissues arise from innermost layer of the shoot apex known as the corpus (L3 layer). The epidermis of roots originates from the layer of cells immediately ...