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Home >> >> Actinomorphic of Flowers-Air Layering
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Actinomorphic (of flowers) - Regular; capable of bisection vertically in two or more planes in to similar halves, e.g., butter cup. Also known as radially symmetrical, a term which is used to describe animals having a similar organiation, e.g., jellyfish. C.f. Zygomorphic.
Actinomycetales - A group of organisms which are intermediate between the bacteria and fungi. There is a fine mycellium which is not exceeding 1.5 in diameter and are Gram positive. Reproduce by fission, arthrospores, and or conidia. The endospores are not formed, and sexual reproduction is not known. Some are responsible for diseases of plants and animals. Some, e.g., Streptomyces produce valuable antibiotics.
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Actinodromous - Describing a form of leaf venation in which three or more veins are originating at the base of the lamina and running out towards the margin. For example, the leaves of 1 Isycamore Acer pseudoplatanus).
Actionomycetales - An order of bacteria having forms that develop a branched mycelium reminiscent of fungal growth forms though on a muchy smaller scale. Most are saprophytic which some are pathogenic.
Actionomycosis - Diseases of cows, sheep, pigs, sometimes taken by man caused by a fungus and marked by the producing of hard masses round the mouth.
Actinostele - A protostele which is stellate in cross-section, having the protoxylem at the tips of the star. A primitive type of stele occurred in the early Pteridophytes.
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Action Spectrum - Gives the relation between the amount of photosynthetic activity for an equal amount of light and the wavelength of the light.
Active Centre (site) - The part of an enzyme molecule that undergoes combination with the substrate. A relatively small number of the atoms of the enzyme molecule gets involved.
Active Transport - Transfer of substance from region of low concentration to where it is high especially across a membrane; takes place by expenditure of energy from metabolism. Proba-bly all cells can do this.
Acuminate - Said of a codition of gradual narrowing to a point in a structure as in certain leaf tips.
Acute - Said of a condition in which structure ends into a sharp I point but is not extending as in the leaf tip of certain leaves.
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Acyl Carrier Protein (ACP) - A low molecular weight conjugated protoein which forms a complex with the enzymes of fatty acid sythesis and binds the acyl group of the growing fatty acid molecule, thereby bringing enzymes and substrate together.
Adaptation - Adjustment of an organism to its environment so that it becomes better fitted for a particular environment. Adaptation may either be acquired during the life of an individual or if governed by the genotype, be inherited.
Adaptive Enzyme - An enzyme formed by an organism especially by bacteria in response to growing on an substrate, i.e., the enzyme is not normally present, but develops soon after growth on the new substrate, i.e., the enzyme is not normally present, but develops soon after growth on the new substrate has started, so that it can be used.
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Adaptor Compound - A carrier compound, e.g. RNA, which is responsible for transferring a substance to the site of reaction.
Adaxial - The surface generally of a leaf, facing the stem. Next to the axis.
Adcrustation - The deposition of a substance on a cell-wall, instead of being laid down between the existing molecules. This latter process is termed as encrusting.
Additive Fixative - A fixative that undergoes chemical combination with the protein of the material to be preserved.
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Adeciduate - Not dediduous.
Adelphogamy - Union between a vegetative mother-cell one of its daughter cells.
Adelphous - Used for androecium in which the filaments are fused. Also see monoadelphous, diadelphous, polyadelphous.
Adenosine Diphosphate (ADP) - The diphosphate ester of adenosive. It is closely related to adenosine triphosphate in the transfer of energy through 'high energy' bonds during the respiration of earbohydrates. The energy gets released in the production of ester phosphates by the ADP, which is acting as a phosphorylating agent.
Adenosine Monophosphate - A phosphorylated nucleoside having the purine denine and the sugar ribose phosphorylated in 5' position. It takes part in the regulation of glycolysis and gluconeogenesis, thereby promoting the formation of fructolse biophosphate from fructose-6-phosphate (i.e., promoting glycolysis) while inhgibiting the back reaction to fructose biphosphate.
Adhesion - The union of dissimilar organs.
Adnnate - Used for describing organs which are joined together e.g., stamens fused with the petals. Compare conate.
ADP - Adenosine diphosphate.
Adventitious - Used for describing organs which are arising in unexpected position, e.g., roots growing from a leaf.
Adventive - Net being or having becomes natural to a place, said of plants taken from other places.
Adventive Embryo (Adventitious embryogenesis). The formation of an embryo in some position other than within an embryo sac.
Aeciospore - A dikaryotic spore which is formed by certain rust fungi in a small cup-shaped srous, the aecium or aecium or aecidium, e.g., Puccinia graminis.
Aecium - A glabular, cup shaped, tubular or irregular fungus fruit body which gets bursted through the epidermis of the host. Typically it has surrounding sterile fungus membrane the periderm which encloses the fertile portion which produces chains of aeciospores. Typically of the Rust fungi.
Aerating Root - A root of some plants which grows in soft mud.They have aerenchyma, and stand above the surface of the ground acting as ventilating organs.
Aerenchyma - A tissue of unthickened cells which are surrounding large airspaces. The walls formed by the cells are perforated so that the airspaces become continuous throughout the organ. This tupe of tissue is common in hydrophytes.
Aerolae - Used for cracks which get developed in the surface of a crustaceous lichen due to growth strains. These cracks help in aeration.
Aerial Root - A root which is usually arising adventitiously from a stem. Usually it is climbing organ, but may contain chlorophyll, or form a parasitic sucker, thus aiding in nutrition.
Aerobe, Aerobiont - A plant which is needing elemental oxygen for respiration.
Aerobic Respiration - Enzymatic destruction of a substate to release energy, involving elemental oxygen, evolving carbon dioxide and water. Starting material for respiration is glucose which on complete oxidation, yields approximately 700 kcal (38 molecules of ATP) of not energy in aerobic respiration in which 6 molecules of oxygen are consumed and 6 molecules of carbondioxide and water each are evolved. Compare anaerobic respiration.
Aerotaxis - Chemotactic movement in which cell or an organism shows movement in response to stimulus of oxygen.
Aerotropism - Chemotropic movement shown in response to stimulus of oxygen.
Aestivation (Prefloration) - Used for the arrangement of sepals in calyx, petals in corolla or tape1s in perianth whorls in immature condition in a bud. There are different ltypes of aestivations on the basis of the pattern of overlap of units in a whorl. (Fig. 1).
After Ripening - (1) A period through which some seeds have to pass after ripening, before they get germinated. (2) The chemical and physical changes taking place inside a seed or other dormant plant-structure, thereby leading to the development of conditions when growth can commence.
Agamandroecious - Male and neuter flowers persent in the same inflorescence.
Agamogynoecious - Female and neuter flowers present in the same inflorescence.
Agamohermaphrodite - Hermaphrodite and neuter flowers pirsent in the same inflorescence.
Agmospermy - The formation of seeds without the fusion of gametes.
Agamotropic - Used for a flower which does not shut after having once opened.
Agar - A mucilaginous substance obtained from certain red algae,
mainly Gelidium. It is a carbohydrate and used in the form of gel as a microbiological supporting medium.
Age and Area, Theory of - According to this theory, the areas ofdistribution of the members ofa group ofallied species are correlated with their ages as species in any given region.
Aggregate Fruit - A fruit-like structure which is developed from many free carpels ofa single flower (apocarpous gynoecium). It consists ofa number ofseparate fruits. It may be an aggregate ofachenes, berries, drupelets, follicles or samaras.
Agrestal, Agrestis (Latin) - Growing in cultivated land, but not itself cultivated. e.g., a weed.
Air Bladder - (1) A swollen air-filled portion ofthallus which occurs in many members ofthe order Fucales ofbrown algae. They increase buoyancy and help in gaseous exchaI1ge.
(2) Any air-filled protuberance which is developing in pollen grains ofcretain gymnosperms due to separation ofthe layers ofexine e.g., in pollens of pinus. Such structures give characteristic winged apearance tothe pollen and assist in dispersal ofpollen by wind.
Air Cavity, Air Space - (1) Used for a large intercellular space in a leaf into which a stoma is opening.
(2) A cavity in the upper surface ofthe thallus ofsome liverworts which is opening externally by an air-pore and containing chains ofphotosynth etic cells.
(3) A large intercellular space in which air is sotred in some water-plants.
Air Chamber - Used for air-filled cavities which are present beneath upper epidermis in gametophytic thallus ofmany liverworts oforder Marchantiales.
Air Layering - A method ofvegetative propagation used in greenhouse and indoor plants by stimulating root production in a branch while it still remains attached to the parent plant. A shallow cut is made or narrow ring ofbark is removed just below the bud. Cut is made to dust with powder having synthetic, root-promoting auxins and is covered with Sphagnum moss and kept moist surrounded by a plastic sleeve. Root formation is slow and may sometimes take upto two years.
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