Plantagenet Nplan-'ta-jo-natV House of or House of Anjou
Van-jii\ Royal house of England (1154-1485) that provided 14 kings, including six from the cadet houses of Lancaster and York. The line descended from Geoffrey, count of Anjou (died 1151), and the empress Matilda, daughter of the English king Henry I. Some historians apply the name House of Anjou, or Angevin dynasty, to only Henry II, Richard I, and John, and label their successors, including Edward I, Edward II, and Edward III, as Plantagenets. The name may have originated as a nickname (Plante- geneste) for Count Geoffrey, who planted broom shrubs (Latin Genista ) to improve his hunting covers. The Wars of the Roses saw the defeat of the last Plantagenet king, Richard III, in 1485. The legitimate line ended with Edward of Warwick (died 1499).
plantain Tall plant ( Musa paradisiaca) of the banana family that is closely related to the common banana (M. sapientum). Believed to have originated in Southeast Asia, the plantain grows 10-33 ft (3-10 m) tall and has a conical false “trunk” formed by the leaf sheaths of its spirally arranged, long, thin leaves. The green-coloured fruit is larger than that of the banana and contains more starch. Because the starch is maximal before the fruit ripens, the fruit is not eaten raw but is boiled or fried, often with coconut juice or sugar as flavouring. It may also be dried for later use in cooking or ground for use as meal, which can be further refined to a flour. The plantain is a staple food and beer-making crop for East African peoples and is also eaten in the Caribbean and Latin America.
plantain \'plan-t 3 n\ Any of about 265 species of familiar garden, lawn, and roadside weeds in the genus Plantago of the family Plantaginaceae. Distinctively, the leaves lack a proper blade. What appears to be a blade is an expanded petiole (leafstalk), with several parallel main veins, emerg¬ ing at the base of the stalk. Small flowers are borne in spikes or heads atop long leafless stalks. The greater plantain (P. major) provides seed spikes for bird food. Ribwort, or English, plantain (P. lanceolata ) and hoary plantain (P media) are troublesome weeds. Some species have been useful in medicine (e.g., as an ingredient in laxatives).
plantation walking horse See Tennessee walking horse
Plante, (Joseph) Jacques (Omer) (b. Jan. 17, 1929, Shawinigan Falls, Que., Can.—d. Feb. 26, 1986, Geneva, Switz.) Canadian ice-hockey player. A goalie, he recorded a shutout in his first NHL game. He was an integral member of the powerful Montreal Canadiens team that won a record five successive Stanley Cups (1956-60). He was the first goalie to wear a protective face mask (1959). Honoured throughout his 18-year NHL career, he was one of the most successful of all NHL goaltenders.
Planudes \pla-'nu-dez\, Maximus orig. Manuel Planudes (b.
1260, Nicomedia, Byzantine Empire—d. c. 1310, Constantinople) Greek Orthodox scholar, anthologist, and polemicist. He established a school in Constantinople that gained a strong reputation for its humanities curricu¬ lum. His Greek translations of Latin philosophy and literature and of Ara¬ bic mathematics publicized these areas of learning throughout the Greek Byzantine cultural world. Though chiefly known for his theological writ¬ ings, he made a distinctive contribution to the history of Greek literature with his revision of the Greek Anthology, a collection of Greek prose and poetry c. 700 bc-ad 1000.
plasma Vplaz-m9\ Liquid part of blood (including dissolved chemicals but not the cells and platelets). This straw-coloured fluid serves as the blood’s transport medium, helps maintain blood pressure, distributes body heat, and maintains the pH balance in the bloodstream and body. More than 90% consists of water, about 7% proteins, and the rest other sub¬ stances, including waste products of metabolism. Important plasma proteins include albumin, coagulation factors, and globulins, including gamma globu¬ lin and a hormone that stimulates erythrocyte formation. Serum is the liq¬ uid part of the blood that remains after clotting.
plasma Electrically conducting medium in which there are roughly equal numbers of positively and negatively charged particles, produced when the atoms in a gas become ionized (see ionization). Plasma is some¬ times called the fourth state of matter (the first three being solid, liquid, and gas). A plasma is unique in the way it interacts with itself, with elec¬
tric and magnetic fields, and with its environment. It can be thought of as a collection of ions, electrons, neutral atoms and molecules, and photons in which some atoms are being ionized at the same time as electrons are recombining with other ions to form neutral particles, while photons are continuously being produced and absorbed. It is estimated that more than 99% of the matter in the universe exists in the plasma state.
plasmid Vplaz-madN Genetic element not contained within a chromo¬ some. It occurs in many bacterial strains. Plasmids are circular DNA mol¬ ecules that replicate independently of the bacterial chromosome. They are not essential for the bacterium but may give it a selective advantage. Some plasmids determine the production of proteins that can kill other bacte¬ ria; others make bacteria resistant to antibiotics. Plasmids are extremely valuable tools in the fields of molecular biology and genetics, specifically in the area of genetic engineering.
plasmodium \plaz-'mo-de-9m\ Any of the parasitic protozoans that make up the genus Plasmodium, the cause of malaria. Infecting red blood cells in mammals, birds, and reptiles, plasmodia occur worldwide, espe¬ cially in tropical and temperate zones. They are transmitted to humans by the bite of the Anopheles mosquito. From the bloodstream, young plas¬ modia enter liver cells, where they divide and form an adult stage that is then released back into the bloodstream and infects red blood cells. Rapid division of the parasites results in the destruction of the red blood cells, which release toxins that cause the periodic chill and fever cycles typical of malaria.
plaster of paris Quick-setting gypsum plaster consisting of a fine white powder, calcium sulfate hemihydrate, which hardens when moistened and allowed to dry. It is made by heating gypsum to 250-360°F (120-180°C). Used since ancient times, plaster of paris is so called because of its prepa¬ ration from the abundant gypsum found in Paris. It is used to make molds and casts for ceramics and sculptures, to precast and hold ornamental plasterwork on ceilings and cornices, and for orthopedic bandages (casts). In medieval and Renaissance times, gesso (plaster of paris mixed with glue) was applied to wood panels, plaster, stone, or canvas to provide the ground for tempera and oil painting.
plastic surgery Surgery to correct disfigurement, restore function, or improve appearance. It may involve reshaping or moving tissues to fill a depression, cover a wound, or improve appearance. Cosmetic surgery solely to improve appearance is not the main focus of plastic surgery. It is utilized after disfigurement by bums or tumour removal or for recon¬ structive work, and it may involve hiding incisions in skin folds or using buried sutures to hold wounds closed. Reconstructive plastic surgery cor¬ rects severe functional impairments, fixes physical abnormalities, and compensates for tissue lost to trauma or surgery. Microsurgery and com¬ puterized diagnostic imaging techniques have revolutionized the field.
plasticity Ability of certain solids to flow or to change shape perma¬ nently when subjected to STRESSes between those that produce temporary deformation, or elastic behaviour, and those that cause failure of the mate¬ rial, or rupture (see fracture). Plasticity allows a solid under the action of outside forces to become permanently deformed without rupturing; elas¬ ticity enables a solid to return to its original shape after the load is removed. Plastic deformation occurs in many metal-forming processes (rolling, pressing, forging, wire drawing) and in geologic processes (rock folding and rock flow within the Earth under extremely high pressures and at elevated temperatures).