Carbonari, in early 19th-century Italy, members of a secret society (the Carboneria) advocating liberal and patriotic ideas. The group provided the main source of opposition to the conservative regimes imposed on Italy by the victorious allies after the defeat of Napoleon in 1815. Their influence

sugar: Plantation white sugar: …white are produced by a carbonatation purification process, in which carbon dioxide gas (scrubbed flue gas) is injected into juice and reacted with lime to form calcium carbonate, which absorbs and adsorbs nonsugars and is filtered off. Powdered vegetable carbon is sometimes added to increase decolorization.

carbonate, any member of two classes of chemical compounds derived from carbonic acid or carbon dioxide (q.v.). The inorganic carbonates are salts of carbonic acid (H2CO3), containing the carbonate ion, CO23-, and ions of metals such as sodium or calcium. Inorganic carbonates comprise many minerals

carbonate mineral, any member of a family of minerals that contain the carbonate ion, CO32-, as the basic structural and compositional unit. The carbonates are among the most widely distributed minerals in the Earth’s crust. The crystal structure of many carbonate minerals reflects the trigonal

calcite compensation depth: …these are mostly blanketed by carbonate oozes, a biogenic ooze made up of skeletal debris. Carbonate oozes cover about half of the world’s seafloor and are present chiefly above a depth of 4,500 metres (about 14,800 feet); below that they dissolve quickly. In the Atlantic basin the CCD is 500…

geology: Sedimentary petrology: One branch deals with carbonate rocks, namely limestones and dolomites, composed principally of calcium carbonate (calcite) and calcium magnesium carbonate (dolomite). Much of the complexity in classifying carbonate rocks stems partly from the fact that many limestones and dolomites have been formed,

carbonate rock, any rock composed mainly of carbonate minerals. The principal members of the group are the sedimentary rocks dolomite and limestone

micrite, sedimentary rock formed of calcareous particles ranging in diameter from 0.06 to 2 mm (0.002 to 0.08 inch) that have been deposited mechanically rather than from solution. The particles, which consist of fossil materials, pebbles and granules of carbonate rock, and oölites (spherical

geology: Sedimentary petrology: One branch deals with carbonate rocks, namely limestones and dolomites, composed principally of calcium carbonate (calcite) and calcium magnesium carbonate (dolomite). Much of the complexity in classifying carbonate rocks stems partly from the fact that many limestones and dolomites have been formed,

carbonate-apatite, rare phosphate mineral belonging to the apatite series. See

carbonation: …carbon dioxide gas to a beverage, imparting sparkle and a tangy taste and preventing spoilage. The liquid is chilled and cascaded down in an enclosure containing carbon dioxide (either as dry ice or a liquid) under pressure. Increasing pressure and lowering temperature maximize gas absorption. Carbonated beverages do not require…

carbonation, addition of carbon dioxide gas to a beverage, imparting sparkle and a tangy taste and preventing spoilage. The liquid is chilled and cascaded down in an enclosure containing carbon dioxide (either as dry ice or a liquid) under pressure. Increasing pressure and lowering temperature

mineral deposit: Carbonatite deposits: Carbonatites are igneous rocks that consist largely of the carbonate minerals calcite and dolomite; they sometimes also contain the rare-earth ore minerals bastnaesite, parisite, and monazite, the niobium ore mineral pyrochlore, and (in the case of the carbonatite deposit at Palabora in South…

Carbondale, city, Lackawanna county, northeastern Pennsylvania, U.S., on the Lackawanna River. Located in a mountain resort region, it is 16 miles (26 km) northeast of the city of Scranton. Settlers first arrived in the area in the early 1800s. The brothers William and Maurice Wurts, who were coal

Carbondale, city, Jackson county, southern Illinois, U.S. It is situated at the northern edge of the Illinois Ozarks, about 100 miles (160 km) southeast of St. Louis, Missouri. Founded in 1852 by Daniel Brush, a mill owner from nearby Murphysboro, in anticipation of the arrival of the Illinois

Almería: …quarry, plant, and port) at Carboneras Beach (on the east coast near Murcia province). The port, which is sheltered and equipped with modern facilities, is especially busy from August to December because of the export of oranges and grapes. Almería has ferry service to the Spanish exclave of Melilla on…

Ottawa, city, seat (1831) of La Salle county, north-central Illinois, U.S. It lies at the confluence of the Fox and Illinois rivers, about 80 miles (130 km) southwest of Chicago. The site was inhabited by Illinois Indians when it was visited by French explorers Jacques Marquette and Louis Jolliet

carbonic acid, (H2CO3), a compound of the elements hydrogen, carbon, and oxygen. It is formed in small amounts when its anhydride, carbon dioxide (CO2), dissolves in water. CO2 + H2O ⇌ H2CO3 The predominant species are simply loosely hydrated CO2 molecules. Carbonic acid can be considered to be a

carbonic anhydrase, enzyme found in red blood cells, gastric mucosa, pancreatic cells, and renal tubules that catalyzes the interconversion of carbon dioxide (CO2) and carbonic acid (H2CO3). Carbonic anhydrase plays an important role in respiration by influencing CO2 transport in the blood. The

Carboniferous Period, fifth interval of the Paleozoic Era, succeeding the Devonian Period and preceding the Permian Period. In terms of absolute time, the Carboniferous Period began approximately 358.9 million years ago and ended 298.9 million years ago. Its duration of approximately 60 million

black shale, variety of shale that contains abundant organic matter, pyrite, and sometimes carbonate nodules or layers and, in some locations, concentrations of copper, nickel, uranium, and vanadium. Fossils are rare in the shale and either are replaced by pyrite or are preserved as a film of

carbonium ion, any member of a class of organic molecules with positive charges localized at a carbon atom. Certain carbonium ions can be prepared in such a way that they are stable enough for study; more frequently they are only short-lived forms (intermediates) occurring during chemical

chemical industry: Benzene: …it was obtained from the carbonization (heating) of coal, which produces coke, combustible gas, and a number of by-products, including benzene. Carbonization of coal to produce illuminating gas dates back in England to the very early years of the 19th century. The process is still employed in some countries, but…

phosgene, a colourless, chemically reactive, highly toxic gas having an odour like that of musty hay, used in making organic chemicals, dyestuffs, polycarbonate resins, and isocyanates for making polyurethane resins. It first came into prominence during World War I, when it was used, either alone

coordination compound: Carbonyl complexes: Following the discovery of the first metal carbonyl complex, tetracarbonylnickel, Ni(CO)4, in 1890, many compounds containing carbon monoxide coordinated to transition metals have been prepared and characterized. For reasons already discussed, such compounds generally contain metal atoms or ions in low oxidation states.…

carbonyl group, in organic chemistry, a divalent chemical unit consisting of a carbon (C) and an oxygen (O) atom connected by a double bond. The group is a constituent of carboxylic acids, esters, anhydrides, acyl halides, amides, and quinones, and it is the characteristic functional group

nickel processing: From sulfide ores: In carbonyl refining, carbon monoxide is passed through the matte, yielding nickel and iron carbonyls [Ni(CO)4 and Fe(CO)5]. Nickel carbonyl is a very toxic and volatile vapour that, after purification, is decomposed on pure nickel pellets to produce nickel shot. Copper, sulfur, and precious metals remain…

malathion, broad-spectrum organophosphate insecticide and acaricide (used to kill ticks and mites). Considerably less toxic to humans than parathion, malathion is suited for the control of household and garden insects and is important in the control of mosquitoes, boll weevils, fruit flies, and

carborane, any member of a class of organometallic compounds containing carbon (C), boron (B), and hydrogen (H). The general formula of carboranes is represented by C2BnHn + 2, in which n is an integer; carboranes with n ranging from 3 to 10 have been characterized. The first carboranes were

Carborundum, trademark for silicon carbide, an inorganic compound discovered by E.G. Acheson; he received a patent on it in 1893. Carborundum has a crystal structure like that of diamond and is almost as hard. It is used as an abrasive for cutting, grinding, and polishing, as an antislip additive,

Edward Goodrich Acheson: …to commercialize his inventions, including The Carborundum Company, Niagara Falls, N.Y.

aluminum processing: Smelting: A carbothermic approach, the classical method for reducing (removing oxygen from) metallic oxides, has been for years the subject of intense research. This involves heating the oxide together with carbon to produce carbon monoxide and aluminum. The great attraction of carbothermic smelting is the possibility of…

Gabrielle Roy was a French Canadian novelist praised for her skill in depicting the hopes and frustrations of the poor. Roy taught school in Manitoba for a time, studied drama in Europe (1937–39), and then returned to Canada, settling in Montreal, where she worked as a journalist. Her studies of

amide: The carboxamides (R′CONR2), which are derived from carboxylic acids (R′COOH), are the most important group. Sulfonamides (RSO2NR2) are similarly related to the sulfonic acids (RSO3H).

bleeding and blood clotting: Synthesis of blood-clotting proteins: …modified glutamic acid known as γ-carboxyglutamic acid. This enzyme reaction, known as γ-carboxylation, requires vitamin K as a cofactor. γ-Carboxyglutamic acid is a unique amino acid that binds to calcium. In the protein, γ-carboxyglutamic acids form the calcium-binding sites that characterize this form of calcium-binding protein, the vitamin K-dependent proteins.…

carbon monoxide poisoning: …they form a stable compound, carboxyhemoglobin, that decreases the amount of uncombined hemoglobin available for oxygen transport. Carboxyhemoglobin has a characteristic cherry-red colour. In spite of asphyxiation, cyanosis (turning blue) does not occur; the skin is pink or pale and the lips bright red. Indications of carbon monoxide poisoning include…

chemical compound: Carboxylic acids: …functional group known as a carboxyl group.

carboxylic acid: Acidity: …charged ion, RCOO−, called a carboxylate ion.

bleeding and blood clotting: Synthesis of blood-clotting proteins: This enzyme reaction, known as γ-carboxylation, requires vitamin K as a cofactor. γ-Carboxyglutamic acid is a unique amino acid that binds to calcium. In the protein, γ-carboxyglutamic acids form the calcium-binding sites that characterize this form of calcium-binding protein, the vitamin K-dependent proteins. Calcium stabilizes certain structural forms of the…

metabolism: Positive modulation: The carboxylation of pyruvate in higher organisms and the carboxylation of phosphoenolpyruvate in gut bacteria ccurs at a significant rate only if acetyl coenzyme A is present. Acetyl coenzyme A acts as a positive allosteric effector and is not broken down in the course of the…

carboxylic acid, any of a class of organic compounds in which a carbon (C) atom is bonded to an oxygen (O) atom by a double bond and to a hydroxyl group (―OH) by a single bond. A fourth bond links the carbon atom to a hydrogen (H) atom or to some other univalent combining group. The carboxyl (COOH)

carboxylic acid: Acyl halides: The functional group of an acyl halide (acid halide) is an acyl group (RCO―) bonded to a halogen atom. They are named by changing the suffix -ic acid in the name of the parent carboxylic acid to -yl halide. Because…

carboxylic acid: Derivatives of carboxylic acids: The carboxylic acid derivatives discussed here (with the exception of nitriles) share the RCO structure with aldehydes, ketones, and carboxylic acids themselves.

ester, any of a class of organic compounds that react with water to produce alcohols and organic or inorganic acids. Esters derived from carboxylic acids are the most common. The term ester was introduced in the first half of the 19th century by German chemist Leopold Gmelin. Carboxylic acid

coordination compound: Coordination compounds in nature: …metal complexes (metalloenzymes); for example, carboxypeptidase, a hydrolytic enzyme important in digestion, contains a zinc ion coordinated to several amino acid residues of the protein. Another enzyme, catalase, which is an efficient catalyst for the decomposition of hydrogen peroxide, contains iron

pain: Alleviation of pain: Modern nonnarcotic anti-inflammatory analgesic salicylates, such as aspirin (acetylsalicylic acid), and other anti-inflammatory analgesics, such as acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen), and cyclooxygenase (COX) inhibitors (e.g., celecoxib), are less potent than opiates but are nonaddictive. Aspirin, NSAIDs, and COX inhibitors either nonselectively or selectively block the activity…

carbuncle, in medicine, a type of inflammatory staphylococcal infection of the skin. A carbuncle typically consists of two or more interconnected boils called furuncles; these are painful red nodules that form yellowish heads which burst to release pus and dead tissue. Carbuncles, however, are

carbuncle, in mineralogy, a deep red, cabochon-cut almandine, which is an iron aluminum garnet. See

carburetor, device for supplying a spark-ignition engine with a mixture of fuel and air. Components of carburetors usually include a storage chamber for liquid fuel, a choke, an idling (or slow-running) jet, a main jet, a venturi-shaped air-flow restriction, and an accelerator pump. The quantity of

carburetor, device for supplying a spark-ignition engine with a mixture of fuel and air. Components of carburetors usually include a storage chamber for liquid fuel, a choke, an idling (or slow-running) jet, a main jet, a venturi-shaped air-flow restriction, and an accelerator pump. The quantity of

carburizing, form of surface hardening (q.v.) in which the carbon content of the surface of a steel object is

motion-picture technology: History: John Carbutt manufactured the first commercially successful celluloid photographic film in 1888, but it was too stiff for convenient use. By 1889 the George Eastman company had developed a roll film of celluloid coated with photographic emulsion for use in its Kodak still camera. This…

isocyanide, any of a class of organic compounds having the molecular structure R―N+ ≡ C, in which R is a combining group derived by removal of a hydrogen atom from an organic compound. The isocyanides are isomers of the nitriles; they were discovered in 1867 but have never achieved any large-scale

wolverine, (Gulo gulo), member of the weasel family (Mustelidae) that lives in cold northern latitudes of North America and Eurasia, especially in timbered areas. The wolverine is noted for its strength, cunning, fearlessness, and voracity, and the species is renowned for its ability to face down

pillory, an instrument of corporal punishment consisting of a wooden post and frame fixed on a platform raised several feet from the ground. The head and hands of the offender were thrust through holes in the frame (as were the feet in the stocks) so as to be held fast and exposed in front of it.

Western sculpture: Late Baroque: …in the proto-Rococo figures of Filippo Carcani in Rome and, to a lesser extent, in those of Filippo Parodi in Genoa, Venice, and Naples. Outside Venice and Sicily the true Rococo made little headway in Italy.

military technology: Special-purpose shot: …for special purposes included the carcass, canister, grapeshot, chain shot, and bar shot. The carcass was a thin-walled shell containing incendiary materials. Rounds of canister and grapeshot consisted of numerous small missiles, usually iron or lead balls, held together in various ways for simultaneous loading into the gun but designed…

meat processing: Hogs: …skin is left on the carcass after the slaughter process. Therefore, after bleeding, the carcasses undergo an extensive cleaning procedure. First they are placed for about five minutes in a scalding tank of water that is between 57 and 63 °C (135 and 145 °F) in order to loosen hair…

Carcassonne, town, capital of Aude département, Occitanie region, southwestern France, southeast of Toulouse, near the eastward bend of the Aude River, which divides the city into two towns, the Ville Basse and the Cité. The Cité has the finest remains of medieval fortifications in Europe. On the

Cesare Pavese: …experience later recalled in “Il carcere” (published in Prima che il gallo canti, 1949; in The Political Prisoner, 1955) and the novella Il compagno (1947; The Comrade, 1959). His first volume of lyric poetry, Lavorare stanca (1936; Hard Labor, 1976), followed his release from prison. An initial novella, Paesi…

carcharhinid, any member of the shark family Carcharhinidae, which includes 12 genera and about 50 species found worldwide. Carcharhinids are found primarily in warm and temperate ocean waters, though a few species inhabit fresh or brackish water. The Carcharhinidae is one of the largest families

carcharhinid, any member of the shark family Carcharhinidae, which includes 12 genera and about 50 species found worldwide. Carcharhinids are found primarily in warm and temperate ocean waters, though a few species inhabit fresh or brackish water. The Carcharhinidae is one of the largest families

carcharhinid: …classification of many, especially the gray sharks, or whalers (Carcharhinus), is uncertain and may be revised after further study.

Galapagos shark, (Carcharhinus galapagensis), shark species belonging to the family Carcharhinidae. Galapagos sharks are considered to be a circumtropical species with strong preferences for warm, clear waters near reef systems or oceanic islands and generally over continental shelf areas. Although

bull shark, (Carcharhinus leucas), species of large predatory shark found in shallow coastal lagoons, estuaries, and harbours in tropical and subtropical oceans and seas worldwide. The bull shark is one of only a few shark species also capable of living and breeding in freshwater environments. Bull

carcharhinid: …are the small blacktip (Carcharhinus limbatus), which grows to about 2.5 meters (8.2 feet), and the somewhat larger large blacktip, or spinner shark (C. brevipinna). One small species, C. melanopterus, is found in shallow Indo-Pacific waters. The International Union for Conservation of Nature and Natural Resources (IUCN) lists each…

shark: Hazards to humans: (Galeocerdo cuvier), bull, oceanic whitetip (C. longimanus), blue, and hammerhead. Of course, the larger the shark, the more formidable the attack, but several small specimens can be hazardous as well, a fact well attested to by seasonal attacks off the southeastern coast of the United States.

carcharhinid: …somewhat larger large blacktip, or spinner shark (C. brevipinna). One small species, C. melanopterus, is found in shallow Indo-Pacific waters. The International Union for Conservation of Nature and Natural Resources (IUCN) lists each of these as vulnerable species.

carcharhinid: One small species, C. melanopterus, is found in shallow Indo-Pacific waters. The International Union for Conservation of Nature and Natural Resources (IUCN) lists each of these as vulnerable species.

Galapagos shark: Natural history: …similar to that of the dusky shark (C. obscurus), a shark with which it is often confused, though the dorsal fins of the Galapagos shark are somewhat larger. The pectoral fins of the Galapagos shark are longer and more pointed, and it has a very wide and rounded snout.

sand tiger shark, any of three species of sharks classified in the genera Carcharias and Odontaspis in family Odontaspididae (order Lamniformes), named for their predatory habits and tendency to frequent inshore habitats in tropical and temperate oceans worldwide. The name sand tiger shark

megalodon, (Carcharocles megalodon), member of an extinct species of megatooth shark (Otodontidae) that is considered to be the largest shark, as well as the largest fish, that ever lived. Fossils attributed to megalodon have been found dating from the early Miocene Epoch (which began 23.03 million

white shark, (Carcharodon carcharias), any member of the largest living species of the mackerel sharks (Lamnidae) and one of the most powerful and dangerous predatory sharks in the world. Starring as the villain of movies such as Jaws (1975), the white shark is much maligned and publicly feared.

white shark: Evolution: mako sharks—starting with Carcharodon hastalis. C. hastalis had teeth similar in size and shape to those of modern white sharks but without serrations. These first white sharks likely first appeared during the middle of the Miocene Epoch. (However, some studies suggest that they may have evolved during the…

white shark: Evolution: hastalis to C. hubbelli (between 8 million and 6 million years ago) and then later to C. carcharias (that is, modern white sharks) in a single evolutionary lineage, or chronospecies. Fossil discoveries suggest that tooth serrations characteristic of modern white sharks appeared gradually in the chronospecies, showing…

megalodon, (Carcharocles megalodon), member of an extinct species of megatooth shark (Otodontidae) that is considered to be the largest shark, as well as the largest fish, that ever lived. Fossils attributed to megalodon have been found dating from the early Miocene Epoch (which began 23.03 million

Carcharodontosaurus, (genus Carcharodontosaurus), genus of massive predatory dinosaurs that inhabited North Africa approximately 99–94 million years ago during the Cenomanian Age (100.5 to 93.9 million years ago) of the late Cretaceous Period (145 to 66 million years ago). Carcharodontosaurus

Paul Sereno: …skull of a specimen of Carcharodontosaurus saharicus. Carcharodontosaurus had been described prior to World War II, but all specimen materials were destroyed during the 1944 bombing of Munich. The theropod was among the largest carnivorous dinosaurs described at 13.7 metres (45 feet) long.

Carchemish, ancient city-state located in what is now southern Turkey, along the border with Syria. Carchemish lay on the west bank of the Euphrates River near the modern town of Jarābulus northern Syria, and 38 miles (61 km) southeast of Gaziantep, Turkey. It commanded a strategic crossing of the

Jeremiah: Life and times: Near the time of the Battle of Carchemish, in 605, when the Babylonians decisively defeated the Egyptians and the remnant of the Assyrians, Jeremiah delivered an oracle against Egypt. Realizing that this battle made a great difference in the world situation, Jeremiah soon dictated to his scribe, Baruch, a scroll…

ambush bug: The Asian genus Carcinocoris is covered with spines. Members of Phymata are among the most-common North American representatives; they frequently are seen lurking on garden plants.

cancer: Molecular evaluation: …diagnostically useful tumor markers include carcinoembryonic antigen (CEA), which is an indicator of carcinomas of the gastrointestinal tract, lung, and breast; CA 125, which is produced by ovarian cancers; CA 19-9, which is an indicator of pancreatic or gastrointestinal cancers; and alpha-fetoprotein and chorionic

carcinogen, any of a number of agents that can cause cancer in humans. They can be divided into three major categories: chemical carcinogens (including those from biological sources), physical carcinogens, and oncogenic (cancer-causing) viruses. Most carcinogens, singly or in combination, produce

biological development: Normal and abnormal development: …is nearly always retrogressive, is carcinogenesis, the production of tumours. Carcinogenesis involves a change in the developmental behaviour of a group of cells. Initially, it often involves a loss of some of the functional and structural characteristics that previously appeared in the cells. It is commonly followed, however, by the…

carcinoma, a cancerous growth of surface (epithelial) tissues of the skin, digestive tract, blood vessels, and various organs. Carcinoma cells tend to invade surrounding healthy tissues and give rise to secondary growths (metastases) distant from the original tumour. In addition to the skin and

esophageal cancer: Diagnosis and prognosis: …esophageal cancer is also called carcinoma in situ and is confined to the inner layer of epithelial cells lining the esophagus. Stage I cancers have spread into the connective tissue layer below the epithelium but have not invaded the underlying muscle layer. Stage II cancers either have spread through the…

horseshoe crab: Natural history: …the mangrove horseshoe crab (Carcinoscorpius rotundicauda)—are found along Asia from Japan to India and closely resemble Limulus in both structure and habits. The animals are most abundant in estuarine waters, where they feed on algae, marine worms, clams and other mollusks, and dead fish.

library: Vehicles for catalogs: …was the creation of a card catalog, each entry having its own card and each card containing only one entry. In principle, such catalogs can grow in size indefinitely; any new entry can be filed between any two existing entries. Thus the catalog offers the opportunity to have a completely…

Willem Dafoe: The Lighthouse, Poor Things, and Nosferatu: film noir Nightmare Alley and The Card Counter, a crime drama directed by Paul Schrader.

card game, game played for pleasure or gambling (or both) with one or more decks of playing cards. Games using playing cards exploit the fact that cards are individually identifiable from one side only, so that each player knows only the cards he holds and not those held by anyone else. For this

domino, simple gambling card game playable by two to eight players. The full deck of 52 cards is dealt out singly, so some hands may contain one more card than others. All players ante an agreed amount to a betting pool. In some circles anyone dealt one card fewer than others must ante an extra

Fernand Léger: That year he completed The Card Party, which was based on sketches of his fellow soldiers. He regarded this work as “the first picture in which I deliberately took my subject from our own epoch.”

Paul Cézanne: Development of his mature style: …Woman with Coffee-Pot (1890–94), and The Card Players (1890–92). This last painting portrays a theme that Cézanne treated in five different versions. Except for the card-player paintings, in which the sober dignity of the men is well expressed, there is no attempt in Cézanne’s portraits to hint at the sitter’s…

Hale Woodruff: …best-known work of that period, The Card Players (1929), shows the stretched human forms and flattened skewed perspective typical of that movement.

cotton: Cotton fibre processing: …loose untwisted rope known as card sliver. For higher-quality yarn, card sliver is put through a combing machine, which straightens the staple further and removes unwanted short lengths, or noils. In the drawing (drafting) stage, a series of variable-speed rollers attenuates and reduces the sliver to firm uniform strands of…

David Card Canadian-American economist who was awarded one-half of the 2021 Nobel Prize for Economics (the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel) “for his empirical contributions to labour economics.” The other half of the prize was awarded jointly to the

David Card Canadian-American economist who was awarded one-half of the 2021 Nobel Prize for Economics (the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel) “for his empirical contributions to labour economics.” The other half of the prize was awarded jointly to the

playing cards, set of cards that are numbered or illustrated (or both) and are used for playing games, for education, for divination, and for conjuring. Traditionally, Western playing cards are made of rectangular layers of paper or thin cardboard pasted together to form a flat, semirigid material.

bittercress, (genus Cardamine), large genus of annual or perennial herbs of the mustard family (Brassicaceae), native to northern temperate areas. Bittercress plants bear white, pink, or pale purple four-petaled flowers in a terminal cluster and produce dry fruits known as siliques. Some—such as

bittercress: Cut-leaved toothwort (C. concatenata), from the same area, has a whorl of three stem leaves. Each leaf is deeply cut into three narrow, bluntly toothed segments.