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Home >> Botany Dictionary >> Maceration - Medullary
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Maceration. Used for a process in which a specimen is prepared for microscopy by chemical dissolution of the matrix binding parts of the specimen, usually by using strong acids. Isolated portions are then examined or subjected to further processing.
Macrandry - Used for describing the phenomenon where male and femal reproductive organs grow on normal sized plants of similar size and structure. Species showing macrandry are termed macrandrous.
Macroconidium - (1) A long, or large condium.
(2) The larger, generally more diagnostic conidium of a fungus, which is having microconidia in addition.
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Macrocyclic - Used for rusts which have 2 alternative hosts, and all the stages in the life-cycle.
Macrofibrils - Said of fibrils found in the cell wall. These are sometimes large enough to be visible under light microscope and composed of microfibrilswhich are lying parallel to each other.
Macrofungi - Fungi having large fruit-bodies.
Macrogamete - A large gamete having food reserves, i.e., the female gamete.
Macrogametophyte - Used for describing the larger of the gametophytes of the heterosporous pteriodphytes. It produces the female gametes.
Macronutrient (essential element). Said of any element which is required by the plant in relatively large amounts for its normal growth. Examples of such elements are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulphur, Magnesium, calcium and iron.
Macrosclereid - Used for describing the relatively short sclerenchyma cell (sclereid), somewhat columnar in shape and forms the outer layer of seed coat in many plants.
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Major Gene - Said of any gene which is controlling a readily identifiable expression of phenotype. Existence of different alleles of such gene gives rise to qualitatively varying phenotypes in regard to the character governed by the gene. All Mendelian factors constitute examples of major genes.
Compare polygene.
Malacophylly - Used for the condition in which leaves of the plant are thick, soft and spongy and store water in their water storage tissue e.g.,
Begonia, Kalanchoe, Bryophyllum etc.
Malate Shuttle - Used for the mechanism which is proposed to explain transfer of reducing substance NADPH across membranes of chloroplast.
NADPH produced by light reactions in photosynthesis reduces oxaloacetate in chloroplast stroma to malate and this then passes across the membrances to cytosol. In the cytosol malate is oxidized to oxaloacetate and NADP is again reduced to NADPH. Oxaloacetate again passes back into the chloroplast stroma to start to the cycle again.
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Male - Used for the organism or the reproductive part which is forming the reproductive apparatus which produces microspores or antherozoids.
Maleic Hydrazide - A growth inhabitor which is usally used as a herbicide or to inhibit sprouting.
Male Sterility - Used for condition in which the production of viable pollens in plant has been prevented by mutation in one or more genes governing their formation. It finds use in plant breeding as a method of ensuring cross pollination and thus forming F1 hybrids.
Malpighian Cell. One cell of a layer of closely packed, radially directed thick-walled cells occurring in the testas of some seeds.
Maltase - An enzyme which is breaking maltose into its two component glucose molecules.
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Malthusian Parameter - Use for describing a measure of the relative rate of population increase or decrease when in the appropriate steady state.
Maltose - A disaccharide sugar (C1 22011) which is made up from the condensing of two D-glucose molecules, in the 1 : 4 a-position.
Mangrove - Used for describing association of plants of the muddy swamps at the mouth of rivers and elsewhere in the tropics, over which the tide flows daily, thereby leaving the mud bare at low tide.
Mannon - A polymer of D-mannose.
Mannitol - A sugar-alcohol of mannose.
CH2OH HO-C-H
HO-C-H
H-C-OH
H-C-OH
CH2OH D-Mannitol
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Mannos. A hexose sugar.
CHO
H-C-OH
H-C-OH
HO-C-H
HO-C-H
CH2OH L-Mannose
MannuronicAcid - Describing a type of uronic acid which occurs in seaweed gum alginic acid. See also alginic acid, uronic acid.
Manubrium - Used. for describing the tubular struture which arises on the inner walls of antheridium in algae of charophyta.
Manure - Said of the exreta of animals which is usually mixed. with other material especially straw and used. to improve soil fertility by adding it to soil.
Maquis - The woodland that is dominated. by stunted. trees (scrub woodland). It is found in semiarid regions which are deforested for agriculture by fire.
Marginal Effect - Describing the phenomenon of more vigourous growth which is shown by plants growing at the edges of a stand of vegetation than the growth of plants present in the centre of the stand.
Marginal Meristem - Said of the meristematic tissue which is located along the edges of a leaf primoridium. Activity of its initials produces mesophyll and epidermal tissues of the lamina.
Marginal Placentation (ventral placentation). Describing the type of placentation in which placentae develop along the ventral suture of a simple, monocarpellary, monolocular ovary e.g., in pods of Leguminosae.
Margo - Said of the zone of thickened sexine present around a colpus in a pollen grain.
Marsh - Describing the region of vegetation in which water table is just at the soil surface. The common plants in his region are water lilies reeds, sedges and various types of grasses.
Mass Flow Hypothesis - The theory postulating that there occurs the translocation of sugars from source to sink in the phloem due to continuous flow of water with dissolved sugars. Osmotic pressure at source becomes high due to continuous formation of sugars and it becomes low at the sink due to continuous use of these. Difference in water potentials of source and sink drives continuous water flow.
Massulae - Used for describing the mucilaginous extensions of tapetum which are surrounding microspores and megaspores in water ferns of genus Azolla.
Mastigonema - Said of any of the numerous hairlike lateral rodlets which are attached to the main rod in a pleuronematic flagellum. These get arranged in longitudinal rows, oriented at an angle and give flagellum a feathery appearance at high magnification.
Maternal Inheritance - Said of the occurrence of hereditable differences referable to materials transmitted by the egg, but not through the male gamete. This occurs due to cytoplasmic inheritance.
Mating Continuum - An aggregate of individuals whose genes systematically undergo recombination.
Mating Group - A group of individuals, haploid or diploid, within which mating gets favoured at the expense of mating outside the group, by genetic or environmental conditions characteristic of group.
Mating Strain - Said of the group of organisms of a species that are characterized by their failure to interbreed with each other. but are able to breed with members of other group of the same species that are morphologically identical but genetically and physiologically different. Both these groups are known as mating strains and usually denoted by symbol+ for male and-for female strain. The differences in mating strains are genetically ascertained.
Matric potential - Generally represented by symbol ψm. Defined as the potential expressing absorptive affinity of water to surfaces and colloidal substances due to surface and capillary forces existing in cells, tissues and soil.
Matorral - A xerophilous shrub community which is found on leached add soil in Spain and Portugal.
Matrix - (1) An outer layer of stainable meterial present in a chromosome.
(2) Any substratum, living or dead, in which a fungus grows.
m-Chromosome - Said of a very small chromosome, many of which may be present in the nuclei of mosses. Their function is not known with certainty.
Meadow - Used for describing a region of moist grassland which could be maintained at the subclimax stae by mowing. Similar areas maintained at subclimax by grazing are known as pastures.
Mechanical Tissue - Said of any tissue which is consisting of cells with thickened walls such as collenchyma and scalrenchyma.
Medium - A nutritive substance on, or in which, tissues or cultures of microorganisms may be grown.
Medulla - (1) The central part of an organ, e.g., the pith of a stem.
(2) A tangle of loose hyphae in a sclerotium, rhizomorph, or any other large fungal structure.
(3) A loose hyphal layer in a thallus of a lichen.
Medullary - Relating to or belonging to the pith.
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