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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]
Phellogen is defined as the meristematic cell layer responsible for the development of the periderm. Cells that grow inwards from there are termed phelloderm, and cells that develop outwards are termed phellem or cork (note similarity with vascular cambium). The periderm thus consists of three different layers: [1] [2]
The periderm forms from the phellogen which serves as a lateral meristem. The periderm replaces the epidermis, and acts as a protective covering like the epidermis. Mature phellem cells have suberin in their walls to protect the stem from desiccation and pathogen attack. Older phellem cells are dead, as is the case with woody stems.
Epidermal organogenesis, the formation of the epidermis, begins in the cells covering the embryo after neurulation, the formation of the central nervous system. In most vertebrates , this original one-layered structure quickly transforms into a two-layered tissue ; a temporary outer layer, the embryonic periderm , which is disposed once the ...
The dark horizontal lines on silver birch bark are the lenticels. [1]A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of gymnosperms and dicotyledonous flowering plants. [2]
Suberin is a lipophilic, complex polyester biopolymer of plants, composed of long-chain fatty acids called suberin acids and glycerol.Suberin, interconnected with cutins and lignins, also complex macromolecules, form a protective barrier in the epidermal and peridermal cell walls of higher plants.
Guard cell – one of the paired epidermal cells that control the opening and closing of a stoma in plant tissue. Heartwood – the older, nonliving central wood of a tree or woody plant, usually darker and harder than the younger sapwood. Also called duramen. Herbaceous – non-woody and dying to the ground at the end of the growing season.
The neural tube cells give rise to the central nervous system, neural crest cells give rise to the peripheral and enteric nervous system, melanocytes, and facial cartilage, and the epidermal region will give rise to the epidermis, hair, nails, sebaceous glands, olfactory and oral epithelium, and eyes.