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Home >>Botany Dictionary >> Partial Parasite - Periclinal
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Partial Parasite - A plant having at least some power of photosynthesis, but obtaining some material salts and water, from a host.
Partial Umbel - One of the smaller groups of flowers which altogether make-up a component umbel.
Partial Veil - Used for agarics, a layer of tissue joining the pileus edge to the stipe during the development of the hymenium. It may later form the annulus or cortina.
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Particulate Inheritance - Inheritance, in one individual, of distinctive characteristics from both parents.
Partspore - One of the one-called spores resulting from the breaking up of a two-or-more-celled ascospore.
Passage Cell - An unthickened cell in the endodermis of a root which is found opposite the protoxylem element, through which solutions can diffuse in a transverse direction.
Patristic - Refers to the condition of similarity existing between two or more taxa which is due to their common ancestry. The concept of such relationships is purely phylogenetic and does not associtate with construction of phylogenetic classifications.
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Pathoge - Refers to any agent that causes a disease in a living organism when present in association with it internally or externally. Term is usually limited to disease causing organisms like fungi, bacteria and protozoa etc.
Peat Refers to the accumulation of partly decomposed plant matter, due to the lack of oxygen, i.e., waterlogging, not allowing the bacteria that bring about decomposition, to live.
Pectic Compounds - Refer to the polysaccharides which are present in the cell-walls of unlignified tissue. They are soluble in water, and form gels under certain conditions. A=arabinose; GA=glacturonic acid; G=galactose; MGA=methylated galacturonic acid
MGA-O
MGA -O-A -O- -O-
MGA-O-GA-O-A
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Pectic Sheath - A lager of pectose which is formed on the outside of the cellulose cell-wall of the Chlorophyta.
Pectin - Refers to the structural polysaccharide in plant cell walls which are rich in a-(14) linked galactouronic acid residues though other sugars e.g., thamnose may also be present.
Pectinase - An enzyme which is destroying the pectin of the middle lamella of cell-walls. It is produced by many parasitic fungi.
Pectinate - Comb-like.
Ped - Refers to the large aggregates of soil particles that are bound by sticky and glutinous organic matter. Peds are important in making and maintaining a particular soil structure and making soil more fertile.
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Pedalfer - A soil which is developed under humid conditions. There occurs no accumulation of calcium carbonate, but the clay complex is differentiated (or tends to differentiate) into horizons, there by resulting in the accumulation of sesquioxides.
Pedate Leaf - A plamately divided compound leaf which is having three main divisions, and having the outer divisions one or more times.
Pedafid - Having the lamina which is deeply cut in a pedate manner.
Pedicel - (1) The stalk of an individual flower of an inflorescence.
(2) A small stalk.
Pedicel Cell - A large basi-cen tral cell present in the globute of the Charaless. It bears all the other structures of the globule, which have been derived by division of a cell at its apex.
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Pedicellate - (1) Said of a flower or a fruit which is having a stalk.
(2) Having a stalk.
Pedicellate - (1) Said of a flower or a fruit which is having a stalk.
(2) Having a stalk.
Pedigree - A table of ancestry or of posterity.
Pedigree Method - Refers to a technique in plant breeding which is used to produce entirely new varieties of plants incorporate ting the best qualities of as selected existing varieties. This method is limited to self-pollinated species.
Pedocals - A group of soils, usually associated with drier climates, and having a freely drained profile with a horizon of calcium carbonate.
Pedogamy - Pseudomixis between mature and immatre cells, as in certain yeasts.
Pedogenesis - Reproduction in young or immature organisms.
Pedogenic Factor - The factors affecting the final appearance of a soil profile, Le., parent material, climatic factors, topography, vegetation and time.
Pedology - Refers to the study of the structure, properties and development of soil body.
Peduncle - Refers to the main axis of inflorescence on which flowers are borne.
Peg - An outgrowth from the hypocotyl of seedings of some curbitaceae. It assists the seeding to emerge from the testa.
Pellicle - (1) Refers to the outer layer of the upper surface of a pilleus, when it can be stripped off as a delicate membrane.
(2) Of bacteria, a growth on the surface of a liquid culture.
Pelagic - Refers to the organ m living in upper layers of water in a sea or ocean such as plankton.
Pellicle (Periplast). Refers to a membrane surrounding the protoplast in some unicellular algae that does not have cell wall e.g., Euglena. .
Pellucid - Refers to anything that is transparent.
Peltate - Refers to a structure which is circular in shape and having a stalk in its centre e.g., leaf of Trapaeolum majas or sporangiophore in Equisetum.
Penetrance - Used for describing the proportion of individuals homozygous for a particular gene which show the phenotype for that gene.
Penetrance of many genes is practically 100% but in other cases, it is much less, the value being affected by the environment or geneotype.
Penicillic Acid - An antibiotic which is produced by Penicillium puberlum and P. cyclopium.
Penicillin - An antibiotic which is produced by strains of Penicillium notatum, and P. chrysagenum.
Penicilliopsin. A yellow pigment which is produced by Penicilliopsis clavariiformis.
Penfamerouss - Refers to a flower in which number of units in each whorl is five or its multiple. It occurs in dicotyledonous plants.
Pentosans - Said of any polysaccharide which is having pentoses as the major constituent subunits. Most common monosaccharides occurring in pentosans are xylose and L-arabinose.
Pentose - Refers to any of the 5-carbon sugars e.g., ribose,deoxyribose, xylose and arabinose that are synthesized from hexoses in pentose phosphate pathway, from CO2 in Calvin cycle or by decarboxylation of nucleic diphosphate sugars.
PentosePhosphatePathway - (phosphogluconate pathway, hexose monophosphate shunt). Represents a multifunctional pathway in which there occurs oxidation of glucose and formation of 3-,4-,5-,6-,7-, carbon sugars. Glucose 6-phosphate is oxidized. and decarboxylated to yield a 5-carbon sugar with formation of NADPH. This sugar now undergoes various combinations and transformations thereby resulting in the reformation of glucose 6-phosphate.
pentoxylales - An order of extinct gymnosperms from Jurassic having uncertain affinities. PEP. (phosphoenolpyruvate). Refers to the phosphorylated intermediate of glucose metabolism. In glycolysis, it is the precursor of pyruvic acid while in synthesis of glucose from acetyl CoA, PEP is formed from oxaloacetate produced in glyoxylate cycle. In C4 plants, it acts as an intermediate in Hatch-Slack pathway.
Pepo - A fleshy or succulent fruit, often of large sie which is formed from aninferior syncarpous ovary, and having many seeds. It is a particular type of berry, e.g., a cucumber.
Peptidase - Said of any hydrolase enzyme catalysing hydrolysis of peptides. Exopetidases attack terminal peptide bonds, en dopeptidases attack bonds within the peptide chains.
Peptide - Refers to any molecule having a humber of amino acids which are linked covalantly by peptide linkage.
Peptide Linkage - The bond between two amino acids in which the amino (NH2) group of one is joining with the carboxyl (COO H) group of the next to give a - NH - CO -linkage between them, with the elimination of water.
Perennation - The survival from season to season, generally with a period of reduced activity between each season.
Perennial - A plant that is living for three or more seasons, and normally flowering and fruiting at least in the second and subsquent seasons.
Perfect - (1) Said of a flower which is having both functinal anthers and ovules.
(2) Said of the stage in the life-cycle of a fungus which produces spors by sexual fusion.
Perfoliate - Said of a leaf base surrounding a stem completely so that the latter appears to pass through it.
Perforation Plate - Refers to the remains of the end walls between two adjacent vessel elements in a xylem vessel which form an opening between two vessel elements. Such plates occur in some ferns, some gymnosperms (Gnetales) and most angiosperms.
Perianth - (1) The floral envelop, it includes the calyx and corolla. or anyone of them.
(2) The cup-shaped or tubular sheath which is surrounding the archegonia of some liverworts.
Periblem - The tissue at the growing point of a stem or root which is lying between the dermatogen and plerome. It gives rise to the cortex.
Pericarp - (1) A layer of vegetative tissue which is covering a fruitbody, as in some fungi.
(2) The body of a fruit developed from the ovary wall, and enclosing the seeds.
Pericentral Cell. A cell which is cut off in a radial plane and is found in the thalli of some Rhodophyta.
Perichaetial Bract - One of the 1eaves' composing the perichaetium in a moss.
Perichaetium. (1) A cup-like sheath which is surrounding the archegonia in some liverworts.
(2) The group of 'leaves' which are surrounding the sex organs of some mosses. They are closely, and somewhat different in structure from the normal 'leaves'.
Perichylous. Having water-storage tissue which is surroundings the chlorophyll-containing tissue.
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