affirmative action: …California Civil Rights Initiative (Proposition 209), which prohibited all government agencies and institutions from giving preferential treatment to individuals on the basis of their race or sex. The Supreme Court effectively upheld the constitutionality of Proposition 209 in November 1997 by refusing to hear a challenge to its enforcement.…

California: California since c. 1900: …2008, when California’s voters approved Proposition 8, a statewide ballot initiative that banned same-sex marriage. As a result of the proposition, a new amendment was added to the state constitution specifying that only marriage between a man and a woman would be recognized by the state. Several lawsuits challenging the…

formal logic: General observations: …is that of a valid proposition form. A proposition form is an expression of which the instances (produced as before by appropriate and uniform replacements for variables) are not inferences from several propositions to a conclusion but rather propositions taken individually, and a valid proposition form is one for which…

John Hurt: …century included the Australian western The Proposition (2005), the futuristic thriller V for Vendetta (2006), the action-adventure movie Indiana Jones and the Kingdom of the Crystal Skull (2008), and the espionage drama Tinker Tailor Soldier Spy (2011). He also appeared as the wand maker Ollivander in multiple installments of the…

propositional attitude, psychological state usually expressed by a verb that may take a subordinate clause beginning with “that” as its complement. Verbs such as “believe,” “hope,” “fear,” “desire,” “intend,” and “know” all express propositional attitudes. The linguistic contexts created by their

propositional calculus, in logic, symbolic system of treating compound and complex propositions and their logical relationships. As opposed to the predicate calculus, the propositional calculus employs simple, unanalyzed propositions rather than terms or noun expressions as its atomic units; and,

connective, in logic, a word or group of words that joins two or more propositions together to form a connective proposition. Commonly used connectives include “but,” “and,” “or,” “if . . . then,” and “if and only if.” The various types of logical connectives include conjunction (“and”),

propositional function, in logic, a statement expressed in a form that would take on a value of true or false were it not for the appearance within it of a variable x (or of several variables), which leaves the statement undetermined as long as no definite values are specified for the variables.

epistemology: The nature of knowledge: …knowledge, often referred to as propositional knowledge, raises a number of peculiar epistemological problems, among which is the much-debated issue of what kind of thing one knows when one knows that something is the case. In other words, in sentences of the form “A knows that p”—where “A” is the…

propositional calculus, in logic, symbolic system of treating compound and complex propositions and their logical relationships. As opposed to the predicate calculus, the propositional calculus employs simple, unanalyzed propositions rather than terms or noun expressions as its atomic units; and,

formal operational stage, stage of human cognitive development, typically beginning around age 11 or 12, characterized by the emergence of logical thinking processes, particularly the ability to understand theories and abstract ideas and predict possible outcomes of hypothetical problems. The

formal logic: Basic features of PC: …Hence they are often called propositional variables. It is assumed that every proposition is either true or false and that no proposition is both true and false. Truth and falsity are said to be the truth values of propositions. The function of an operator is to form a new proposition…

history of logic: Syllogisms: …to what is called the logic of propositions. Aristotle’s logic is, by contrast, a logic of terms in the sense described above. A sustained study of the logic of propositions came only after Aristotle.

Italian literature: Opposing movements: Monti, its leader, issued Proposta di alcune correzioni ed aggiunte al vocabolario della Crusca (1817–26; “Proposal for Some Corrections and Additions to the Crusca Dictionary”), which attacked the Tuscanism of the Crusca. By contrast, the patriot Pietro Giordani—for a time a journalistic colleague of Monti—was a great exponent of…

myth: Formalist: …myths, the 20th-century Russian folklorist Vladimir Propp investigated folktales by dividing the surface of their narratives into a number of basic elements. These elements correspond to different types of action that, in Propp’s analysis, always occur in the same sequence. Examples of the types of action isolated by Propp are…

Sir James Black: …development of two important drugs, propranolol and cimetidine.

proprietary colony, in British American colonial history, a type of settlement dominating the period 1660–90, in which favourites of the British crown were awarded huge tracts of land in the New World to supervise and develop. Before that time, most of the colonies had been financed and settled

proprietary software, software developed by an individual or company that chooses not to publicly share the program’s source code. This allows the software’s creator to control its distribution. One of the key features of proprietary software is that it is legally owned by the individual,

e-book: How e-books are distributed: …distribution would occur within closed, proprietary systems, where e-book buyers or library patrons would have to get their books directly from a small number of owners of e-book files.

property: …in a thing was called dominium, or proprietas (ownership). The classical Roman jurists do not state that their system tends to ascribe proprietas to the current possessor of the thing but that it did so is clear enough. Once the Roman system had identified the proprietarius (the owner), it was…

Edward Waring: In 1762 Waring published Miscellanea analytica… (“Miscellany of analysis…”), a notoriously impenetrable work, but the one upon which his fame largely rests. It was enlarged and republished as Meditationes algebraicae (1770, 1782; “Thoughts on Algebra”) and Proprietates algebraicarum Curvarum (1772; “The Properties of Algebraic Curves”). It covers the theory…

proprioception, the perception by an animal of stimuli relating to its own position, posture, equilibrium, or internal condition. The coordination of movements requires continuous awareness of the position of each limb. The receptors in the skeletal (striated) muscles and on the surfaces of tendons

human sensory reception: Approaches to the study of sensing: …well-being also rests heavily on proprioceptors (for sensing bodily position) and on the sense of balance. These structures, monitoring bodily orientation in space, provide crucial sensory feedback for guiding movements (see also movement perception).

theatre: Visual and spatial aspects: The earliest properties, such as altars and rocks, could be set up at the edge of the terrace. The first extant drama for which a large building was necessary was Aeschylus’ trilogy the Oresteia, first produced in 458 bce. There has been controversy among historians as to…

exophthalmos, abnormal protrusion of one or both eyeballs. The most common cause for unilateral or bilateral exophthalmos is thyroid eye disease, or Graves ophthalmopathy. The proptosis arises from inflammation, cellular proliferation, and accumulation of fluid in the tissues that surround the

aerospace industry: Propulsion: There are three basic types of flight vehicle-propulsion systems: piston engines (or reciprocating engines), turbine engines (true-jet, turboprop, and turboshaft engines), and rocket engines (see airplane: Propulsion systems; rocket). At the low end of the performance spectrum are reciprocating engines. Although during

jet engine: The propulsor: The efficiency of a propulsor, propulsive efficiency ηp, is the portion of the available energy that is usefully applied in propelling the aircraft compared to the total energy of the jet stream. For the simple but representative case of the discharge airflow equal to the inlet gas flow, it is…

ammunition: propelling charges used in small arms, artillery, and other guns. Ammunition size is usually expressed in terms of calibre, which is the diameter of the projectile as measured in millimetres or inches. In general, projectiles less than 20 mm or .60 inch in diameter are…

jet engine: The propulsor: The efficiency of a propulsor, propulsive efficiency ηp, is the portion of the available energy that is usefully applied in propelling the aircraft compared to the total energy of the jet stream. For the simple but representative case of the discharge airflow equal to the inlet gas flow, it is…

aerospace industry: Propulsion: There are three basic types of flight vehicle-propulsion systems: piston engines (or reciprocating engines), turbine engines (true-jet, turboprop, and turboshaft engines), and rocket engines (see airplane: Propulsion systems; rocket). At the low end of the performance spectrum are reciprocating engines. Although during

jet engine: The propulsor: The gas horsepower generated by the prime mover in the form of hot, high-pressure gas is used to drive the propulsor, enabling it to generate thrust for propelling or lifting the aircraft. The principle on which such a thrust is produced is based on…

propyl alcohol, one of two isomeric alcohols used as solvents and intermediates in chemical manufacturing. The second isomer is isopropyl alcohol (2-propanol). Normal (n-) propyl alcohol is formed as a by-product of the synthesis of methanol (methyl alcohol) from carbon monoxide and hydrogen. It

gallic acid: Propyl gallate is an important antioxidant for the prevention of rancidity in edible oils and fats. Gallic acid is 3,4,5-trihydroxybenzoic acid and has the formula (HO)3C6H2·CO2H.

Johann Wolfgang von Goethe: Friendship with Schiller (1794–1805) of Johann Wolfgang von Goethe: …he started a new journal, Die Propyläen (“The Propylaea”), to preach an uncompromising gospel of the superiority of the ancients to the moderns. It lasted only two years, but in 1799, to carry on its work, he inaugurated a series of art competitions in which subjects from Classical antiquity were…

propylaeum, in ancient Greek architecture, porch or gatehouse at the entrance of a sacred enclosure, usually consisting of at least a porch supported by columns both without and within the actual gate. The most famous propylaeum is the one designed by Mnesicles as the great entrance hall of the

propylene, a colourless, flammable, gaseous hydrocarbon, C3H6, obtained from petroleum; large quantities of propylene are used in the manufacture of resins, fibres, and elastomers (see polyolefin), and numerous other chemical products. See alsopropylene glycol; glycol; propyl

propylene glycol, synthetic organic compound with the chemical formula C3H8O2. Propylene glycol is a colourless liquid that is relatively viscous, has no odour, and tastes slightly sweet. It is hygroscopic, meaning that it readily absorbs water from the surrounding environment. Annual production of

soap and detergent: Nonionic detergents: …group, with ethylene oxide or propylene oxide. The most usual compounds are either alkylphenol or a long-chain alcohol having a hydroxyl group at the end of the molecule. During the condensation reaction, the ethylene oxide molecules form a chain which links to the hydroxyl group. The length of this chain…

hyperthyroidism: Treatment of hyperthyroidism: …methimazole in the body), and propylthiouracil. These drugs block the production of thyroid hormone but have no permanent effect on either the thyroid gland or the underlying cause of the hyperthyroidism. Patients with hyperthyroidism caused by Graves disease are often treated with an antithyroid drug for one to two years…

astrology: Astrology in the Hellenistic period (3rd century bc to 3rd century ad): A second is the prorogator, a point on the ecliptic that, traveling at the rate of one degree of oblique ascension a year toward either the descendant or ascendant, determines a person’s length of life. Another is the method of continuous horoscopy, under which anniversary diagrams are compared with…

James Earl Jones: Voice work and television: …in Gabriel’s Fire (1990–91; retitled Pros and Cons, 1991–92), for which he won an Emmy Award for outstanding lead actor in a drama series. He also earned an Emmy for his role in the TV movie Heat Wave (1990), about the Watts Riots of 1965. Jones continued to make guest…

Life happens, and sometimes you find yourself in a real cash crunch. If you’ve already tapped your emergency funds, a 401(k) loan could be your friend. A 401(k) loan can be less expensive and easier to obtain than some other options. But 401(k) loans still come with potential risks, so you have to

Western philosophy: Skepticism: …ce), wrote a large work, Pros dogmatikous (“Against the Dogmatists”), in which he tried to refute all of the philosophers who held positive views, and in so doing he quoted extensively from their works, thus preserving much that would otherwise have been lost. It is a noteworthy fact that the…

Conon of Samos: He also wrote Pros Thrasydaion (“In Reply to Thrasydaeus”), concerning the intersection points of conics with other conics and with circles. None of his works survive.

froghopper: The two-lined spittlebug (Prosapia bicincta) is one of the most common species in eastern North America. Adults are dark brown with two red-orange stripes and feed on grasses, weeds, and holly. Nymphs are yellow and are often found on grasses in late spring.

Julio Ramón Ribeyro: …fiction, and the essay in Prosas apátridas (1975; “Prose of a Man with No Country”), an introspective examination of his experience in France, had a wide readership, particularly in Peru.

Rubén Darío: Life and work: Darío’s next significant work, Prosas profanas y otros poemas (1896; “Profane Hymns and Other Poems”), a collection of verse, continued the innovative stylistic trends of Azul but treated its exotic scenes and personages in a manner more symbolic than objective, for it was influenced by the contemporary French Symbolist…

Rubén Darío: Life and work: Darío’s next significant work, Prosas profanas y otros poemas (1896; “Profane Hymns and Other Poems”), a collection of verse, continued the innovative stylistic trends of Azul but treated its exotic scenes and personages in a manner more symbolic than objective, for it was influenced by the contemporary French Symbolist…

dinosaur: Sauropodomorpha: …their probable ancestral group, the prosauropods. All were plant eaters, though their relationship to theropods, along with the fact that the closest relatives of dinosaurs were evidently carnivorous, suggests that they evolved from meat eaters. Sauropodomorpha are distinguished by leaf-shaped tooth crowns, a small head, and a neck that is…

dinosaur: Sauropodomorpha: …their probable ancestral group, the prosauropods. All were plant eaters, though their relationship to theropods, along with the fact that the closest relatives of dinosaurs were evidently carnivorous, suggests that they evolved from meat eaters. Sauropodomorpha are distinguished by leaf-shaped tooth crowns, a small head, and a neck that is…

prosbul, (from Greek pros boulē, “in front of the court”), a legal procedure introduced into Judaism by Hillel the Elder in the 1st century bc to permit private loans to persons in need without fear on the lender’s part that the debt would be legally abrogated at the end of the sabbatical year

proscenium, in theatre, the frame or arch separating the stage from the auditorium, through which the action of a play is viewed. In the ancient Greek theatre, the proscenium (Greek: proskēnion) originally referred to a row of colonnades, supporting a raised acting platform (logeion), and afterward

squirrel: Natural history: Others, like the pygmy squirrel of Sulawesi (Prosciurillus murinus), travel and forage at intermediate levels between ground and canopy. Some large tropical squirrels, such as the Sulawesi giant squirrel (Rubrisciurus rubriventer) and the northern Amazon red squirrel (Sciurus igniventris), nest at middle levels but travel and forage low…

prosciutto, highly prized dry-cured ham of Italian origin. Deriving from the Latin perex suctum, meaning “dried out,” prosciutto is used in Italian as the generic term for “ham,” referring to a food whose basic form consists of only two ingredients: a hind leg of a pig and salt. To this is added

prosciutto, highly prized dry-cured ham of Italian origin. Deriving from the Latin perex suctum, meaning “dried out,” prosciutto is used in Italian as the generic term for “ham,” referring to a food whose basic form consists of only two ingredients: a hind leg of a pig and salt. To this is added

proscription, in ancient Rome, a posted notice listing Roman citizens who had been declared outlaws and whose goods were confiscated. Rewards were offered to anyone killing or betraying the proscribed, and severe penalties were inflicted on anyone harbouring them. Their properties were confiscated,

proscription, in ancient Rome, a posted notice listing Roman citizens who had been declared outlaws and whose goods were confiscated. Rewards were offered to anyone killing or betraying the proscribed, and severe penalties were inflicted on anyone harbouring them. Their properties were confiscated,

Pietro Bembo: …Castiglione, and Torquato Tasso; and Prose della volgar lingua (1525; “Discussions of the Vernacular Language”). In the Prose, Bembo codified Italian orthography and grammar, essential for the establishment of a standard language, and recommended 14th-century Tuscan as the model for Italian literary language. His view, opposed by those who wanted…

elf: In the Prose, or Younger, Edda, elves were classified as light elves (who were fair) and dark elves (who were darker than pitch); these classifications are roughly equivalent to the Scottish seelie court and unseelie court. The notable characteristics of elves were mischief and volatility. They were…

literature: Prose fiction: Extended prose fiction is the latest of the literary forms to develop. We have romances from Classical Greek times that are as long as short novels; but they are really tales of adventure—vastly extended anecdotes. The first prose fiction of any psychological depth is…

Julio Ramón Ribeyro: …fiction, and the essay in Prosas apátridas (1975; “Prose of a Man with No Country”), an introspective examination of his experience in France, had a wide readership, particularly in Peru.

prose poem, a work in prose that has some of the technical or literary qualities of a poem (such as regular rhythm, definitely patterned structure, or emotional or imaginative heightening) but that is set on a page as prose. The form was introduced into French literature by Louis Bertrand, with his

Donna Tartt: The Goldfinch: …of Books, writer and critic Francine Prose wondered, “Doesn’t anyone care how something is written anymore?” James Wood of The New Yorker was similarly dismissive.

crime: The decision to prosecute: In countries where the legal system follows the English common-law tradition, the function of prosecution is usually distinguished from that of investigation and adjudication. In most countries the prosecution is performed by an official who is not part of either the police or the…

prosecutor, government official charged with bringing defendants in criminal cases to justice in the name of the state. Although responsibilities vary from one jurisdiction to another, many prosecutors are in charge of all phases of a criminal proceeding, from investigation by the police through

legal profession: Public-directed practice: …the office of the “prosecutor general,” or “officer of justice”; a similar service existed in most of the socialist countries of eastern Europe.

procedural law: Prosecutorial discretion: In all legal systems the prosecutor should bring an accusation only if he thinks that the available evidence, discounted by probable defense evidence, is so strong that the defendant is likely to be convicted after trial. In some countries, such as Italy, the…

St. Peter the Apostle: The position of Peter in the apostolic church: … and be acceptable as a proselyte. In accepting Cornelius and the others—who may have had some informal connection with the synagogue (Acts 10:1)—and ordering “them to be baptized in the name of Jesus Christ” (Acts 10:48) without submission to the prior rite of circumcision, Peter introduced an innovation that ensured…

forebrain, region of the developing vertebrate brain; it includes the telencephalon, which contains the cerebral hemispheres, and, under these, the diencephalon, which contains the thalamus, hypothalamus, epithalamus, and subthalamus. The forebrain plays a central role in the processing of

angiosperm: Ground tissue: Prosenchyma cells are starch-containing parenchymal cells whose cell walls have become lined with lignin, as occurs in the stems of Bougainvillea (Nyctaginaceae). A specialized type of parenchyma cell, called a transfer cell, is involved in the short-distance movement of solutes by cell-to-cell transfer. Transfer cells

Persephone, in Greek religion, daughter of Zeus, the chief god, and Demeter, the goddess of agriculture; she was the wife of Hades, king of the underworld. In the Homeric “Hymn to Demeter,” the story is told of how Persephone was gathering flowers in the Vale of Nysa when she was seized by Hades

dam: The Romans: …Roman dams in southwestern Spain, Proserpina and Cornalbo, are still in use, while the reservoirs of others have filled with silt. The Proserpina Dam, 12 metres (40 feet) high, features a masonry-faced core wall of concrete backed by earth that is strengthened by buttresses supporting the downstream face. The Cornalbo…

dam: The Romans: …Roman dams in southwestern Spain, Proserpina and Cornalbo, are still in use, while the reservoirs of others have filled with silt. The Proserpina Dam, 12 metres (40 feet) high, features a masonry-faced core wall of concrete backed by earth that is strengthened by buttresses supporting the downstream face. The Cornalbo…

Persephone, in Greek religion, daughter of Zeus, the chief god, and Demeter, the goddess of agriculture; she was the wife of Hades, king of the underworld. In the Homeric “Hymn to Demeter,” the story is told of how Persephone was gathering flowers in the Vale of Nysa when she was seized by Hades

Russian literature: Thaws and freezes: …novel Proshchaniye s Matyoroy (1976; Farewell to Matyora) about a village faced with destruction to make room for a hydroelectric plant. The novel’s regret for the past and suspicion of the new dramatically marks the difference between village prose and the Socialist-Realist collective farm novel. Yury Trifonov wrote about what…

Mathias Döpfner: …Springer’s $3 billion acquisition of ProSiebenSat.1, Germany’s largest television concern, marked its first step outside publishing. The merger gave the company access to five German television channels that claimed a combined 45 percent market share and moved the firm into direct competition with the privately owned German media giant Bertelsmann…

Dante: La vita nuova: Each is a prosimetrum—that is, a work composed of verse and prose. In each case the prose is a device for binding together poems composed over about a 10-year period. The Vita nuova brought together Dante’s poetic efforts from before 1283 to roughly 1292–93; the Convivio, a bulkier…

primate: Classification: …order Primates was divided into Prosimii (the primitive primates: lemurs, lorises, and tarsiers) and Anthropoidea (the bigger-brained monkeys and apes, including humans). It is now known that one of the “prosimians,” the tarsier, is actually more closely related to the “anthropoids,” so the classification of the primates has had to…

primate: Classification: …order Primates was divided into Prosimii (the primitive primates: lemurs, lorises, and tarsiers) and Anthropoidea (the bigger-brained monkeys and apes, including humans). It is now known that one of the “prosimians,” the tarsier, is actually more closely related to the “anthropoids,” so the classification of the primates has had to…

proscenium, in theatre, the frame or arch separating the stage from the auditorium, through which the action of a play is viewed. In the ancient Greek theatre, the proscenium (Greek: proskēnion) originally referred to a row of colonnades, supporting a raised acting platform (logeion), and afterward

Khmelnytskyy, city, western Ukraine. It lies along the upper Southern (Pivdennyy) Buh River. Originally a Polish military post, it dates from the late 15th century. The fort was seized by Cossacks during the mid-17th century. In 1793 it passed to Russia by the Second Partition of Poland, and in

Khmelnytskyy, city, western Ukraine. It lies along the upper Southern (Pivdennyy) Buh River. Originally a Polish military post, it dates from the late 15th century. The fort was seized by Cossacks during the mid-17th century. In 1793 it passed to Russia by the Second Partition of Poland, and in

ancient Greek civilization: The conquest of Bactria and the Indus valley: …the Persian court ceremonial involving proskynesis, or obeisance. Just what this entailed is disputed; perhaps it amounted to different things in different contexts, ranging from an exchange of kisses to total prostration before the ruler in the way a Muslim says his prayers. What is not in doubt is that…

history of logic: Theophrastus of Eresus: Such propositions he called prosleptic propositions, and inferences involving them were termed prosleptic syllogisms. Greek proslepsis can mean “something taken in addition,” and Theophrastus claimed that propositions like these implicitly contain a third, indefinite term, in addition to the two definite terms (“α” and “γ” in the example).

history of logic: Theophrastus of Eresus: …inferences involving them were termed prosleptic syllogisms. Greek proslepsis can mean “something taken in addition,” and Theophrastus claimed that propositions like these implicitly contain a third, indefinite term, in addition to the two definite terms (“α” and “γ” in the example).

St. Anselm of Canterbury: Early life and career: His Proslogion (“Address” or “Allocution”), originally titled Fides quaerens intellectum (“Faith Seeking Understanding”), established the ontological argument for the existence of God. In it he claimed that even a fool has an idea of a being greater than which no other being can be conceived to…

broomcorn: …also the common name of Panicum miliaceum, a type of millet.

broomcorn: …also the common name of Panicum miliaceum, a type of millet.

prosobranch, any snail of the subclass Prosobranchia, class Gastropoda. Most of these roughly 20,000 snail species are marine; a few live on land or in fresh water. Many prosobranchs breathe by means of gills, which are located in the mantle cavity in front of the heart; some have a special

prosobranch, any snail of the subclass Prosobranchia, class Gastropoda. Most of these roughly 20,000 snail species are marine; a few live on land or in fresh water. Many prosobranchs breathe by means of gills, which are located in the mantle cavity in front of the heart; some have a special

prosody: The 18th century: Joshua Steele’s Prosodia Rationalis (1779) is an early attempt to scan English verse by means of musical notation. (A later attempt was made by the American poet Sidney Lanier in his Science of English Verse, 1880.) Steele’s method is highly personal, depending on an idiosyncratic assigning of…

suprasegmental, in phonetics, a speech feature such as stress, tone, or word juncture that accompanies or is added over consonants and vowels; these features are not limited to single sounds but often extend over syllables, words, or phrases. In Spanish the stress accent is often used to

prosody, the study of all the elements of language that contribute toward acoustic and rhythmic effects, chiefly in poetry but also in prose. The term derived from an ancient Greek word that originally meant a song accompanied by music or the particular tone or accent given to an individual

arachnid: Body and appendages: …into two distinct regions: the cephalothorax, or prosoma, and the abdomen, or opisthosoma. The sternites (ventral plates) of the lower surface of the body show more variation than do the tergites (dorsal plates). The arachnids have simple (as opposed to compound) eyes.

prosopagnosia, neurological disorder in which affected persons are unable to recognize faces, despite having healthy vision and normal memory and intelligence. The severity of prosopagnosia ranges from mild to severe, from the inability to recognize faces seen only a small number of times to the

Aristolochiaceae: The genus Prosopanche occurs in Central and South America, and Hydnora occurs in Africa, Madagascar, and the Arabian Peninsula. The southern African H. triceps grows exclusively on succulent species of Euphorbia.

mesquite, (genus Prosopis), genus of spiny deep-rooted shrubs or small trees in the pea family (Fabaceae). They form extensive thickets in areas from South America into the southwestern United States. They are considered pests and have been eradicated in some places. The wood of the mesquite,

Thar Desert: Land: The khajri (or khejri) tree (Prosopis cineraria) grows throughout the plains.

desertification: Grazing lands: …in the southwestern United States, honey mesquite (Prosopis glandulosa) is a native shrub, but it can increase its range considerably when cattle overgraze grasslands. The resulting plant community supports few livestock and is a persistent one—that is, the extensive thickets of mesquite often prevent grasses from recolonizing their former range.

Gran Chaco: Plant life: …species, among which the notorious vinal (Prosopis ruscifolia) was declared a national plague in Argentina because its thorns, up to a foot in length, created a livestock hazard in the agricultural lands it was invading.