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Aerenchyma in stem cross section of a typical wetland plant. Aerenchyma or aeriferous parenchyma [1] or lacunae, is a modification of the parenchyma to form a spongy tissue that creates spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases between the shoot and the root. [2]
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.
Parenchyma (/ p ə ˈ r ɛ ŋ k ɪ m ə /) [1] [2] is the bulk of functional substance in an animal organ or structure such as a tumour. In zoology, it is the tissue that fills the interior of flatworms. In botany, it is some layers in the cross-section of the leaf. [3]
In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function [1]. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific ...
Animal tissues are grouped into four basic types: connective, muscle, nervous, and epithelial. [4] Collections of tissues joined in units to serve a common function compose organs. While most animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism.
Restoration Lepidostrobus, the strobilus of Lepidodendron lycophytes. Lepidodendron species were comparable in size to modern trees. The plants had tapering trunks as wide as 2 m (6.6 ft) at their base that rose to about 40 m (130 ft) [2] and even 50 m (160 ft), [1] arising from an underground system of horizontally spreading branches that were covered with many rootlets.
Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. [1] It develops mostly from the mesenchyme, derived from the mesoderm, the middle embryonic germ layer. [2] Connective tissue is found in between other tissues everywhere in the body, including the nervous system.
The epidermis is the outermost cell layer of the primary plant body. In some older works the cells of the leaf epidermis have been regarded as specialized parenchyma cells, [1] but the established modern preference has long been to classify the epidermis as dermal tissue, [2] whereas parenchyma is classified as ground tissue. [3]