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Home >>Botany Dictionary>>Vacuolation - Verruca
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Vacuolation - The process of up taking of large amount of water into the cell vacuole by osmosis during the process of cell elongation.
Vacuole - A fluid - filled space in a cell. In many plant cells, it single vacuole, is taking up most of the volume of the cell. It contains a cell-sap which is isotonic with the protoplasm.
Vagina - A sheathing leaf-base.
Vaginate - Sheathed.
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Vaginule - A minute sheath, which is surrounding the base of the seta in the bryophtes.
Valine - An amino acid which is occurring in proteins.
Valley Bog - Used for the form of bog in regions like glens of western Scotland receiving runoff and spring water from surrounding mountains.
Valvate - Used for the aestivation in calyx and corolla in which individual units have been arranged in cir w, their edges are just touching each other but not overlapping. Compare imbricate.
Vascular Plants - Describing any plant containing vascular con­ducting tissue, i.e., xylem and phloem. These include pterido­phytes, gymnosperms and angiosperms.
Vascular System - The continuous network of vascular tissue, xylem and phloem, that is forming the conducting system through out a plant body.
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Valvular - Used for opening by means of values.
Variation - Used for the differences of characters between individuals assumed to be inherited (genetic) and those due to the effect of environmental factors. In sexually reproducing organisms, genetic variance occurs due the recombination although its ultimate source is mutation and in addition to this, environmental variation ma occur due to various physical and biotic factors and exhibits the phenotypic plasticity of the organism. Variation may occur in kind of characters (qualitative variation) or in the degree of characters (quantitative variation).
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Variegation - Used for irregular variation in colour of a plant organ, e.g., leaves or flower due to the suppression of normal pigment development. This may occur due to the action of a marginal genotype, somatic mutation, or infection.
Vascular Bundle - Stands for one of a number of strands of primary vascular tissue having both xylem and phloem. Vascular bundles together comprise of vascular system of the plant. Vascular bundles may be radial, having xylem and phloem and different radii e.g., in roots conjoint, collateral, bicollateral, concentric etc., in stems. If there is fascicular cambium between xylem and phloem, bundle is called open and if it is absent, bundles are called closed.
Vascular Cambium - Used for lateral meristem found in those vascular plants which are undergoing secondary growth. It forms secondary xylem and secondary phloem mostly by periclinal cell divisions. It is having fusiform initials that form axial system and rav initials that form radial system of secondary tissues. See also fasicular cambium, cambium interfascicular cambium.
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Variety - A group of plants of animal forming part of a species but marked off as a separated division of it by having in common certain properties which are different from the type but developments from it and which are regularly handed on to their off spring when produced by breeding with one another.
Varve - The layer of sediment deposited in a glacial lake by waters which are melted in summers and spring. Varves were formed in Pleistocene when ice was retreating.
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Vascular Transition - The transition of arrangement of vascular tissue from that of the roof to that of stem which is seen in the transition region (See transition region) so as to maintain the continuity of vascular issue throughout the plant.
Vector - The animal carrying a pathogen from one organism to another e.g., aphids, white flies and leaf hoppers. In sect vectors transmit viral and mycoplasma diseases. Mites and nematodes are also vectors of viral diseases.
Vegetation - All the plants grown in a given area.
Vegetative Nucleus (vegetative cell). The large nucleus which is formed within the pollen grain of angiosperms along with one or two smaller generative nuclei. It gets migrated to the tip of pollen tube on pollen germination and may be called tube nucleus. It may probably be controlling the growth and development of pollen tube disintegrates when pollen tube penetrates the nucellus.
Vegetative Reproduction, Vegetative Multiplication, Vegetative Propagation - Asexual reproduction taking place by detachment of part of the plant which is then developed in, to a complete plant.
Veil, Velum - (1) An evanescent membrance present over an apothecium.
(2) A sheath of hyphase which is forming a complete membrane over the fruit-body of an agaric.
Vein - A single vascular bundle or a group of closely associated bundles in a leaf. In a leaf vein, xylem is almost always present on adaxial side whereas phloem is present towards abaxial side. Sometimes vein has been surrounded by a bundle sheath of collenchyma, sc1erencyma or parenchyma which may be extending to the leaf epidermis. The pattern of veins in a leaf is known as venation
Velamen - Water absorbing tissue which is present on the outside of aerial roots in certain plants, e.g., epiphytic orchids. It consists of several layers of dead cells often with spirally thickened and perforated walls, which soak up water running over it.
Velum (veil). A membranous outgrowth from the base of a leaf of Isoetes. It is covering or partly covering the sporangium.
Velutinous - Covered thickly with very short, soft, upright hairs, very smooth and soft to the touch.
Venation (veination). The pattern of veins in a leaf as observed from its upper surface or lower surface. It is of diagnostic value. See also actinodromous, brochidodromous, camplyodromous, craspedromous, eucamptodromous, parallelodromous, reticulodromous.
Venter - The swollen flask-shaped base of an archegonium which is having the female gamete.
Ventral - (1) In thallose plants flattened like a leaf, the lower surface that is towards the ground or substrate.
(2) In lateral organs, the adaxial side. Compare dorsal. See also adaxial. .
Ventral Canal Cell - One of the products which is formed along with egg cell when the primary ventral cell of an archegonium undergoes division. It lacks cell wall and lies at the base of neck. At maturity of archegonium. It becomes mucilaginous and may produce chemicals to attract the male gamete.
Ventral Suture - The line of fusion at which the margins of megasporophylls join to form characteristic tubular shape of ovary as happened in angiosperms. Dehiscence takes place along these sutures at fruit ripening.
Vernalin - A hypothetical plant growth substance assumed to be formed in meristematic regions of a plant subjected to cold and possible taking part in vernalization.
Vernalization - Said of the treatment of plant with low temperatures in the initial stages of seedling development. This treatment induces a rapid development towards a physiologically order condition thereby shortening the interval between sowing and flowering.
Vernation - The manner in which the leaves have been arranged in the bud. Many types of vernation are recognised in Fig. 33.
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