Anything related to plant life Angiosperm Cells and Tissues Angiosperm Cells and Tissues Some cell types and tissues which are not found in any other groups of plants occur in angiosperms flowering plants.
In general, Plant Anatomy refers to study of internal morphology, pertaining to different tissues. The subject of this chapter is structure of Angiosperms, with emphasis on primary tissues. All these parts are made up of different types of tissues containing different cell types. A tissue is a mass of similar or dissimilar cells performing a common function.
The body of a vascular plant is composed of dermal tissue, Ground tissue and Vascular tissue. Dermal Tissue Skin Dermal Tissue is protective in function.
Basing on its origin, it is classified into two types — Epidermis and Periderm. This is the primary surface tissue of the entire plant. Epidermal cells are compactly and continuously arranged; the continuity is lost by the presence of Stomatal pores or breaks in the tissue.
Covering the aerial epidermis, cutin fatty substance is present as an impregnation on cell wall. The cuticle can be separated from epidermis. The epidermis may produce unicellular or multicellular hairy outgrowths and other appendages.
Epidermis provides mechanical protection, allows gaseous exchange through stomata, restricts transpiration with cuticle, and is also involved in storage, photosynthesis, secretion, absorption and perception to stimuli.
Stomata are Pores, each guarded by two guard cells, which control the size of the pore. Cells surrounding guard cells, but differing from other epidermal cells, are called subsidiary cells. Guard cells are kidney shaped; their cell walls are thick on the inner surfaces.
Guard cells contain many chloroplasts.
This is formed during secondary growth replacing primary epidermis. This is inner to dermal tissue and is composed of simple tissues like parenchyma. Vascular tissue Vascular tissue consists of conducting elements — xylem and phloem.
Vascular tissue may be scattered in ground tissue or regularly arranged forming a ring. In the latter arrangement, ground tissue is differentiated into cortex outer to vascular tissue and pith inner to vascular tissue. The ground tissue of leaves is called mesophyll, bound by upper and lower epidermis.
In broad sense, tissues are classified as — meristematic and permanent tissues. Meristem Meristos — divisible Initially all embryonic cells of an embryo have the capacity to divide and multiply but as the embryo develops into a plant body, this capacity for division is restricted to certain parts of the plant body called meristems which are active throughout the life of the plant body unlike that of an animal body.
When meristematic cells divide, a group of the daughter cells remain meristematic; the other daughter cells called derivatives differentiate into various tissue elements. Before the occurrence of any cell division, usually cells become enlarged accompanied with addition of protoplasmic and cell wall material.
Meristematic cells are isodiametric, compactly arranged with dense cytoplasm, large nucleus, and small vacuoles or without vacuoles. Cell walls are thin. Meristems which occur at the apices of stem, root and other branches are called apical meristems, which bring about primary growth of the plants, hence also called as primary meristems.
In many plants in addition to apical meristems, lateral meristems like vascular cambium, cork cambium, intercalary meristems are found. Lateral meristems are arranged parallel to the sides of organs in which they occur. This is also a primary meristem, found inserted between permanent tissues, in the bases of internodes and leaf sheaths of grasses.Leaf: Epidermis with simple stomata (absent in true seagrasses, which are also angiosperms) in the cortex vascular bundles with xylem (including vessel elements) and phloem without companion cells and .
The outer part of the stem tissues is covered with a layer of epidermis. The root system of angiosperms is also very complex. The roots also contain cortex, phloem, xylem, and epidermis.
They prevent fertilization of egg cells by sperm cells with too similar genotypes. At the same time, the intervention of the style enhances pollen tube selection among the entire pollen portion that has been transferred to the stigma in the process of pollination, and therefore, fertilization by the most vigorous male gametophytes.
Epidermis, in botany, outermost, protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant.
The epidermis and its waxy cuticle provide a protective barrier against mechanical injury, water loss, and infection. Epidermis, in botany, outermost, protoderm-derived layer of cells covering the stem, root, leaf, flower, fruit, and seed parts of a plant. The epidermis and its waxy cuticle provide a protective barrier against mechanical injury, water loss, and infection.
Large lipid droplets are present constantly in the leaf epidermis of angiosperms. Earlier they were considered typical only of mesophyll and bundle-sheath cells.
Now they are found in stomata, in particular, in their subsidiary cells.