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Home >>Botany Dictionary>>H - Heterandrous
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H - A flower class, including flowers which are usually zygomorphic having a corolla tube 6-15 mm. long, and suited to pollination by bees.
H-Piece - A short lateral hypha which joins 2 longer hyphae. It is kprobably aiding in the flow of food-materials through the mycelium.
Habit - The general external appearance of a plant.
Habitat - The immediate environment that is occupied by anzorganism.
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Habitat Form - A plant showing features, which are abnormal, but can be related to the place where it is growing, e.g. dwarfing under poor conditions.
Habitat Group - A set of unrelated plants that are occupying the same kind of situation.
Habituation - Said of the process by which an organism gets accustomed to the new environmental conditions to which it has been transferred.
Haem - Used for one of a group of iron-porphyrins, which get conjugated with proteins to form peroxidase, catalase, and all the cytochromes.
Haematochrome - An orangered pigment which is probably a Carotenoid and found in some Cholophyceae.
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Hair - A unior nulticellular epidermal outgrowth which may be absorptive, e.g., root hair, secretory, protective, or reducing the rate of transpiration.
Half-Inferior - Used for a flower in which the receptacle forms a cup which gets jointed to the base of the ovary and partly up its side.
Half-Race - Used for describing race of plants in which only a few of the seedlings exhibit the characteristic of the race, the others have the ordinary characteristic of the species, and in which selection does not result in the fixing of a pure race.
Halophobe - A plant not growing in a soil having an appreciable amount of salt-water.
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Hyte - A plant living in soil having salt water in appreciable amounts, walophhere in consequence, there exists a physiological drought.
Halosere - Used for describing set of several communities which are formed during succession in a low lying region of land originally beneath sea and subsequently silted up with mud, silt and shingle and exposed to periodic tides of sea water thereby possessing high salinity in substratum.
Hapazanthic (monocarpic).- A plant bearing flowers only once during its life-span and after fruit formation, leaves fall off and plant dies.
Haploibiont - (1) A plant having only one type of individual in its life cycle.
(2) Having one type of thallus which is typically haploid.
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Haplocheilic - Said of a gymnospennous stomatal complex where subsidiary cells and guard cells are not originating from the same initials e.g., incycads.
Haploid - Having a single set of unpaired chromosomes.
Haplont - A plant which reproduces sexually, having a diploid zygote, while all the other cells are haploid.
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Haplophase - The haploid stage in he life cycle of plants under going an alternation of generations.
Haplopolyploid - A plant that is derived from a polyploid by haploid parthenogenesis, and therefore having half the number of chromosomes of the original polyploid.
Haplosis - Said of the halving of the number of chromosomes at meiosis.
Haplostele - A protostele, having a smooth circular outline in transverse section.
Hapteron - A cell, or cellular organ which is attaching a plant to the substrate. Used especially of the Thallophyta.
Haptonasty - A movement which is induced, by touch, but, not influenced by the direction of the stimulus.
Haptonema - Used for describing the thread like structure that is found between two flagella in the algal members of Haptophyta and not involved in cell movement but remains coiled during cell movement in some cases. It may be used for temporary anchorage.
Haptotropism - A tropism which takes place in response to contact, e.g., a tendril twining around the object it has touched.
Hard Bast - Sclerenchyma that is produced in the phloem.
Hard Pan - An impenetrable layer which is formed in the B-horizon of soil.
Hardening - Said of the gradual exposure of a plant to lower temperaturers for increasing its tolerance and resistance to frost. Seedlings grown in green houses are usually hardened by placing them in cold frames and gradually increasing the ventilation before they are planted outside.
Hard Seed - Said of any seed which has a tough, impervious outer seed coat that does not allow imbibition and entry of water into the seed. Germination in such seeds needs rupturing of seed coat either by scarification or microbial action as in Lathyrus odoratus.
Hardy-Weinberg Law - According to this la w the random mating of individuals is equivalent to the random union of gametes.
Harting Net. In an ectotrophic mycorrhiza, the mycellium inside the cells of the root disintegrates, thereby leaving a net work of hyphae in the inter cellular spaces (the Hartig net). From this the mycellium grows out to form a sheathh over the root.
Hastate - (1) Having two somewhat out turned lobes at the base.
(2) Halbertshaped.
Hatch-Slack Pathway - Describing an alternative form of CO2 fixation in C4 plants having first product of CO2 fixation as 4-carbon ozaloacetate which is formed by carbozylation of phosphoenol pyruvate by PEP carboxylase. Reactions take place in mesophyll cells and products get transferred to bundle sheath cells where they form CO2 again by decarbolation which is then fixed by normal Calvin cycle reactions in bundle sheath cells. Pyruvate from bundle sheath cells returns to mesophyll cells to be converted to PEP involving conversion of ATP into AMP. As PEP carboxylase has higher affinity for CO2 than RuBP carboxlase, C4 plants have higher efficiency of CO2 fixation than C3 plants.
Haulm - A stem of a grass.
Haustorium - A specialized branch of organ of a parasite, which penetrates the host tissue, and absorbs nutrients and water.
Head - A group of conidia and sterigmata crowded into a dens mass, which is rounded in outline.
Heartwood - The central xylem of tree-trunks which is frequently impregnated with tannins, resins etc. It can be considered to be excretory products. It does not have living cells.
Heath - Said of a region which is exposed to strong winds and is having well drained, poor, sandy soil and having absence of trees though region in being surrouned by forests.
Heavy Metal Tolerance - Used for the ability shown by certain plants to grow in areas that are having high concentrations 6f heavy metals such as copper, lead and zinc where other plants fail to grow.
Helical Thickening (spiral thickening). Said of a type of patterning of secondary wall thickening in tracheary elements in which secondary wall has been laid down in a spiral band. It makes further extension of cell like the annular thickening and is, therefore, occurred in protoxylem elements that are still elongating.
Heliophyte - Used for a plant that shows better growth and there fore, prefers sunny places.
Heliotropism - Used for describing the specific type of phototropism which implies such movement in response to sunlight rather than artificial light.
Helophyte - Describing a marsh plant having its perennating buds which are situated in the mud at the bottom of the pond or lake e.g., Typha.
Helotissm - A form of symbiosis, in which one partner is benefitted more than the other, e.g., the fungus in a lichen thallus benefits more than the alga.
Hemiangiocarpic - (1) Describing the fruit body of a fungus, when the hymenium begins its development enclosed, but is exposed at maturity
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(2) Used for a sporocarp, which opens just before it is mature.
Hemiautophyte - A parasite having chlorophyll, so that it can manufacture some carbohydrates.
Hemicelluloses - Said of carbohydrates related to cellulose, but are mixed polysaccharides, having other sugars besides glucose. They get easily hydrolysed by dilute acids.
Hemicryptophyte - A plant having its buds just above, or below the soil surface, where they are protected.
Hemicycc1ic - Said of a flower having some parts in spirals, and others in whorls.
Hemizygous - Describing the situation where normal diploid nucleus is having only one copy of a particular gene (or chromosome). Thus the un paired section of X-chromosome is termed as hemizygous.
Herbaceous Perennial - A perennial plant surviving during unfavourable winter as underground perennating organ such as rhizome, corm, bulb or tuber which is producing foliage leaves and flowers only in favourable season but again die at the onest of unfavourable season.
Herbicide (weed killer) - Any chemical that on application to a plant, particularly herb, either destroys it or seriously inhibits its growth.
Hercogamy, Herkogamy - Describing the condition of a flower, in which the stamens and stigmas are so placed, that self-pollination becomes impossible.
Heredity - The process by which the qualities of the parents are passed on to the offslpring.
Heritability - Describing the proportion of total variance of an observable characteristic which may be accounted for by genetic factors.
Hermaphrodite - (monoclinous). A plant having both male and female reproductive organs in the same flower of some individual.
Hesperidium - A fleshy fruit which is formed from a superior, syncarpous gynoedum. The flesh is formed from fluid-filled haris projecting into the loculi, e.g. an orange.
Heterandrous - Having stamens which are not all of the same size.
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