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Habituation to a specific practice, such as drinking alcoholic beverages or using drugs (for example, heroin, cocaine, or amphetamines), and disorders characterized by the chronic use of a drug, alcohol, or similar substance. Addiction and addictive…

Any disorder of recognition. Agnosia is a rare neurological condition in which an individual fails to recognize and identify persons or objects (see illustration). Typically, agnosia is the result of damage to specific areas of the brain.…

A disease of the nervous system characterized by a progressive dementia that leads to profound impairment in cognition and behavior. Dementia occurs in a number of brain diseases where the impairment in cognitive abilities represents a decline from…

A significant, yet relatively selective loss of memory. Amnesia is a type of memory loss, often resulting from brain disease or injury (see illustration). The inability to remember can be temporary or permanent. In general, amnesia can be…

A disorder of language acquired as a result of brain disease. Aphasia is impairment in the use of spoken or written language caused by brain disorders (see illustration) that cannot be explained by paralysis or incoordination of the articulatory…

An impairment in the performance of voluntary actions despite intact motor power and coordination, sensation and perception, and comprehension. Apraxia is a neurological condition in which there is difficulty with skilled tasks or learned movements…

A neurodevelopmental condition that impairs the way that a person relates to and communicates with other people. Persons with autism have difficulties with social communication and interaction. They also can have unusual behaviors, such as…

Any of several leguminous plants, or their seeds, long utilized as food by humans or livestock. There are more than 40,000 varieties of beans, with only a small number of these being mass-produced for human or animal consumption. In particular,…

A coarse, erect, annual herb plant, Ricinus communis, belonging to the spurge family (Euphorbiaceae). The castor plant (Ricinus communis) is a member of the spurge family (Euphorbiaceae) in the order Malpighiales. The plant varies greatly in height…

Any member of the grass family (Poaceae or Gramineae) that produces edible grains usable as food by humans and livestock. Cereals are important cultivated crops. Common cereals include rice, wheat, barley, oats, maize (corn), sorghum, rye, and…

An evergreen shrub or small tree, particularly Cinnamomum verum, and the spice obtained from the plant's bark. The cinnamon plant (see illustration) is a member of the laurel family (Lauraceae) in the order Laurales. Native to Sri Lanka, the…

The biological study of insects that have a direct influence on humanity. Economic entomology is a subdiscipline of entomology (the biological science that deals with the investigation of insects) and focuses on the effects of insects on human…

The controlled induction of a grand mal seizure under anesthesia to treat individuals suffering from certain psychiatric illnesses. Electroconvulsive therapy (ECT; Fig. 1) was introduced as a treatment for psychiatric disorders by the Italian…

The segment of horticulture concerned with the commercial production, marketing, and sale of plants grown and used for decorative or display purposes. Floriculture is a branch of horticulture, that is, the art and science of growing plants,…

The science, art, and practice of managing and using the natural resources that occur on and in association with forested lands. Forestry is the management of forested lands (see illustration). It involves the planning and implementation of…

Plants that have altered genetic material (DNA) through recombinant DNA (rDNA) manipulation. Genetic engineering of plants allows for very specific genetic changes to be made to a plant's deoxyribonucleic acid (DNA), as opposed to the random…

Commercially grown plants that have altered genetic material through artificial recombinant manipulation. Genetic modification is the latest scientific tool for developing improved crop varieties. Such genetically modified (GM) crops can help to…

An organism that has had its genetic material manipulated or altered in a laboratory setting through the use of genetic or genomic engineering techniques. Genetically modified organisms (GMOs) are microorganisms, plants, or animals that have been…

The artificial application of water to the soil to produce plant growth. Irrigation also cools the soil and atmosphere, making the environment favorable for plant growth. The use of some form of irrigation (Fig. 1) is well documented throughout the…

An annual leafy leguminous vine, Pisum sativum (order Fabales), cultivated for its smooth or wrinkled, round edible seeds, which are borne in dehiscent pods. The garden pea (Fig. 1) is one of the world's oldest cultivated crops. It is a native of…

The planning and implementation of actions to establish, protect, restore, and maintain trees and forests in cities and smaller communities. When the field of urban forestry began in the 1960s, it focused on individual trees along streets and…

Wildfires are a natural phenomenon in many ecosystems, including forests along the U.S. Pacific West Coast, as natural fires serve to rejuvenate ecological communities. However, from mid-August through mid-September 2020, forests in California,…

A group of psychiatric conditions, also known as mood disorders, that are characterized by disturbances of affect, emotion, thinking, and behavior. Affective or mood disorders are strong mental disturbances that interfere with daily life (Fig. 1).…

A branch of meteorology that examines the effects and impacts of weather and climate on crops, rangeland, livestock, and various agricultural operations. Agricultural meteorology, or agrometeorology, addresses topics that often require an…

The pure and applied science that is concerned with botany and management of crop and ornamental plants for utilization by humankind. As it relates to plants, agricultural science concerns itself with the application of scientific methods to…

The art and science of crop and livestock production. In its broadest sense, agriculture comprises the entire range of technologies associated with the production of useful products from plants and animals, including soil cultivation, crop and…

The science and study of crops and soils. Agronomy is the umbrella term for a number of technical research and teaching activities (see illustration): crop physiology and management, soil science, plant breeding, and weed management frequently are…

A psychiatric disorder in which a dramatic reduction in caloric intake consequent to excessive dieting leads to significant bodily, physiological, biochemical, emotional, psychological, and behavioral disturbances. Anorexia nervosa is one of three…

A group of distinct psychiatric disorders including generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, social anxiety disorder, specific phobia, and posttraumatic stress disorder. Whereas fear is an adaptive emotion that is…

A deciduous tree (genus Malus) in the order Rosales, which produces an edible, simple, fleshy, pome-type fruit. Apples (Fig. 1) belong to the family Rosaceae, which includes many other deciduous fruits, including pears, peaches, and cherries. There…

Vegetables that are prevalent in Asian cuisines, but less well known in Western diets. Asian vegetables (Fig. 1), also referred to as Asian greens or oriental vegetables, are very important in Asian countries, but are not as popular in North America…

Wildfires, also termed bushfires or forest fires, are currently devastating large swaths of land in Australia. Detrimental ecologic consequences of these uncontrolled combustions of forest fuels and vegetation are numerous. One of the most serious…

A large tropical plant of the genus Musa and its edible fruit. The banana belongs to the family Musaceae (order Zingiberales). The banana of commerce (Musa acuminata), which is believed to have originated in the Asian tropics, was one of the…

The American beech (Fagus grandifolia) is native to forest regions east of the Mississippi River and is a key tree species in the United States. In particular, it is very abundant from Ohio to the New England states. The tree is also found in the…

The management and maintenance of colonies of honeybees for human purposes. Beekeeping is an ancient art. Although the commonly known honeybee species (Fig. 1) is native to Europe and Africa, humans have transported them to other continents. The…

The study of the hereditary factors that shape behavior. Behavior genetics, that is, the scientific investigation of the hereditary factors that influence behavior, may be studied in animals and humans. Charles Darwin, who originated the theory that…

Many questions concerning the sustainable production of biofuels have emerged over recent years in terms of land and water use, pollution from fertilizer and pest-control chemicals, greenhouse-gas production, net energy production, and whether…

The use of parasitoids, predators, and pathogens to reduce injurious pest insect populations and consequently the damage that they cause. Biological insect control (or insect biocontrol) is the regulation of insect populations by biological means.…

Unwanted, aggressive behavior that involves a real or perceived power inequity. The behavior of bullying is often chronic and includes actions such as threats, spreading rumors, attacking someone physically or verbally, and purposefully excluding or…

A biennial umbellifer (Daucus carota) of Asiatic and Mediterranean origin belonging to the plant order Apiales. The carrot (Daucus carota; Fig. 1) is grown for its edible roots, which are eaten raw or cooked. Cultivated forms of the root vegetable…

A group of trees belonging to the madder family (Rubiaceae), occurring indigenously in the cool, cloud forests of the Andes from Colombia to Peru. Many species of cinchona (genus Cinchona) have been described. Most are variants of C. pubescens (see…

The visual perception of different wavelengths of light. Light can be understood both as electromagnetic waves and as particles called photons. Photons can have different energies. The energy of a photon determines the frequency and wavelength of…

Equipment used in the production and processing of milk and milk products, including milking machines, cream separators, coolers, pasteurizers, homogenizers, butter-making equipment, evaporators and dryers, and related items of equipment. Dairy…

A general term for a genus of tall forage grasses, of which the most important species is the deeply rooted perennial Paspalum dilatatum. Dallis grass (see illustration) is widely grown in the southern United States, mostly for pasture, and remains…

Common name for the plant Colocasia esculenta, including the variety antiquorum (taro). Dasheen plants are among the few edible members of the aroid family (Araceae). Native to southeastern Asia and Malaysia, the plants supply local inhabitants with…

The date palm, Phoenix dactylifera, which is one of the oldest cultivated tree crops. The date palm provides a staple food for many populations in the Middle East and North Africa and is also highly valued for feed, fiber, and shelter. Beginning in…

Defoliants are chemicals that cause leaves to drop from plants; defoliation facilitates harvesting. Desiccants are chemicals that kill leaves of plants; the leaves may either drop off or remain attached; in the harvesting process the leaves are…

The division of forestry concerned with taxonomy of trees and other woody plants. The term dendrology is derived from the Ancient Greek: dendron (= tree) and -logia (= study of or science of); the term xylology is used occasionally to denote the…

A genus of tropical shrubs belonging to the legume family [Leguminosae (Fabaceae)]. Plants of the genus Derris (see illustration), with their long branches climbing over other vegetation, occur as members of the jungle undergrowth in Southeast Asia,…

A form of cognitive-behavioral therapy. Dialectical behavior therapy (DBT) is a psychotherapy developed by psychologist Marsha M. Linehan in the 1990s and designed originally to treat borderline personality disorder (BPD). DBT derives from a…

An annual culinary herb, genus Anethum, of the carrot family, Apiaceae (Umbelliferae). Dill supplies four products: dill seed oil, dill leaf oil, dill seed, and dill leaf. Although all dill grown in the United States is one species, Anethum…

Any of the tree or shrub species in the genus Cornus. The tree, Cornus florida, also known as the flowering dogwood, may reach a height of 40 ft (12 m) and is found in the eastern half of the United States and in southern Ontario, Canada. It has…

A large coniferous tree, Pseudotsuga menziesii (formerly, P. taxifolia), known also as red fir, belonging to the pine family (Pinaceae). Douglas-fir is one of the most widespread and most valuable tree species of western North America and ranks…

Any tree of the genus Diospyros of the ebony family, containing more than 250 species. Some species of ebony are important for their succulent fruits, such as date plum, kaki plum, and persimmon, and several are important for timber, particularly…

Those organ systems of the animal body which mediate overt behavior. Injury to an effector system leads to loss or to subnormal execution of behavior patterns mediated by the system, conditions termed paralysis and paresis, respectively.Overt…

A warm-season vegetable (Solanum melongena) of Asiatic origin belonging to the plant order Solanales (formerly Polemoniales). Eggplant is grown for its usually egg-shaped flesh fruit (see illustration), which is eaten as a cooked vegetable. Cultural…

Any species of Ulmus, a genus of hardwood trees in the Northern Hemisphere, with simple, serrate, deciduous leaves. The American or white elm (U. americana) is the most important species (Fig. 1). It is a large, typically vase-shaped tree that…

The empirical method is not sharply defined. It is generally characterized by the collection of a large amount of data before much speculation as to their significance, or without much idea of what to expect, and is to be contrasted with more…

A genus of low, leafless, green-stemmed shrubs belonging to the order Ephedrales, and the source of the drug ephedrine. Plant members of the Ephedra genus grow in dry, alkaline soils around the world. In the southwestern United States, these plants…

A large and important Australian forest tree, including about 700 species in the family Myrtaceae. Eucalyptus trees (eucalypts; genus Eucalyptus) occur throughout Australia and are particularly prevalent in eastern areas of the continent. However,…

Foeniculum vulgare, a culinary herb of the parsley family (Apiaceae). Fennel is grown for the dried, ripe fruits or seeds, which are used as a spice in breads, pickles, liqueurs, and meat sauces and dishes. Although similar in odor to anise, fennel…

Materials added to the soil, or applied directly to crop foliage, to supply elements needed for plant nutrition, and the management of this nutrient application to sustain maximum plant growth and yield while minimizing environmental impacts of…

A group of grasses belonging to the genus Festuca used for both hay and pasture. There are approximately 100 species of fescue, and more than 30 are represented in the United States. Tall fescue (F. arundinacea; alternatively Lolium arundinaceum),…

Plants grown for their fibrous material, which is used for many commercial purposes and for home industry. Many plants are grown as fiber crops because of their content or yield of fibrous material, which is used in the manufacture of textiles,…

A species of deciduous tree, Ficus carica, of the mulberry family (Moraceae). The fig tree is of southwest Asian origin and is now cultivated in the subtropical regions of the world for its edible fruit, especially in Asia, Africa, Europe, and the…

A nut from any plant in the genus Corylus; also called hazelnut. About 15 species are recognized; they are distributed widely over the North Temperate Zone and range in size from shrubs to tall trees. Filberts in commerce are derived mostly from the…

Any tree of the genus Abies, of the pine family, characterized by erect cones, the absence of resin canals in the wood but with many in the bark, and flattened needlelike leaves that lack definite stalks. Fir leaves usually have two white lines on…

An erect annual plant, Linum usitatissimum, cultivated as a source of flaxseed and fiber. The flax plant (Linum usitatissimum) [Fig. 1] is the source of two products: flaxseed for linseed oil and fiber for linen products. Plants with two distinct…

Grasses and legumes that make up grasslands and are consumed by grazing livestock. The grasslands represent an ancient renewable natural resource. They form 25% of the world's vegetation and occupy the largest area of any single plant type. They…

Application of the theories, constructs, and analytical methods of linguistics to questions that arise in civil, criminal, and security investigations and adjudication. Understanding linguistics as a social science is essential, because almost all…

The trees, shrubs, herbs, bacteria, fungi, and animals, together with the surrounding air, soil, water, organic debris, and rocks (environmental substrate), interacting inside a defined boundary. Forests and woodlands occupy about 38% of the Earth's…

The application of engineering principles and practices to facilitate the sustainable management of forests. Forest engineering commonly includes responsibility for securing forest raw materials for processing into products or services at an…

The subdiscipline of genetics concerned with genetic variation and inheritance in forest trees. The study of forest genetics is important because of the unique biological nature of forest trees (large, long-lived plants covering 30% of the Earth's…

The science and practice of measuring the volume, growth, and development of trees individually and collectively and estimating the products obtainable from them. Foresters use quantitative sciences such as mathematics and statistics for these…

The use of forests for recreation is increasing. For many people, outdoor recreation involves direct contact with forests in various activities ranging from walking in the woods to wilderness backpacking. The primary suppliers of forest recreation…

The natural medium for growth of tree roots and associated forest vegetation. Weathering of underlying rock, climatic factors (such as rain, wind, and temperature fluctuations), living organisms, topography, and disturbances (such as glacial action,…

The timber produced by temperate, boreal, and tropical forests around the world. Timber is included in a wide variety of industrial and other commodities that are traded in national and international markets. United States resources Of the total…

Any edible fruit borne on a tree. Tree fruits include temperate, subtropical, and tropical zone species. Most temperate-zone fruit trees are deciduous, that is, they lose their leaves in the autumn. They are grown principally in regions protected…

The application of biotechnological techniques utilizing fungi for agricultural purposes. Fungal biotechnology is applied in agriculture to promote plant vigor, to increase yields, and to reduce impacts of plant diseases, weeds, or invertebrate…

Synthetic or biosynthetic compounds used to control fungal diseases in animals and plants. A fungistat prevents the spread of a fungus, whereas a fungicide kills the fungus. Agricultural fungicides Chemical compounds are used to control plant…

A hardy perennial, Allium sativum, of Asiatic origin and belonging to the plant order Asparagales. Garlic is grown for its pungent bulbs (see illustration). Segments of these are used primarily for seasoning. Europeans have grown garlic for probably…

An important spice or condiment; also the plant from which it is obtained, Zingiber officinale, of the ginger family (Zingiberaceae). The plant is a native of southeastern Asia. It is an erect perennial herb (see illustration) having thick, scaly,…

The common name for a group of perennial herbs in the genus Panax, belonging to the aralia family (Araliaceae), native to the woodlands of the North Temperate Zone and cultivated for the aromatic root of the plant, which has been used medicinally in…

An agricultural business concerned with breeding goats, primarily for meat, milk, and fiber (called mohair and cashmere). Goats are even-toed ungulates (hoofed mammals) belonging to the genus Capra (order Artiodactyla). Domesticated goats (Capra…

Crop plants that belong to the grass family (Poaceae or Gra­mineae), generally grown for their edible starchy seeds. Grain crops also are referred to as cereal crops and include wheat, rice, corn (maize), barley (see illustration), rye, oats,…

The common name for plants of the genus Vitis characterized by climbing stems and grown for the edible, pulpy berries. The common grapevine Vitis vinifera (Fig. 1) has intermittent forked tendrils, a bark that sheds, a diaphragm at the node, and…

Citrus paradisi, an evergreen tree belonging to the order Sapindales and having a well-rounded top cultivated for its edible citrus fruit, which is large, globose, and characterized by a yellow rind and white, pink, or red pulp. The grapefruit…

Members of the family Poaceae (Gramineae) cultivated as forage and grain for consumption. The grasses are the most useful of all the plants that cover the Earth. The cereal grass crops [wheat (Fig. 1), rice, corn (maize), rye, barley, oats, sorghum,…

A glass- or plastic-enclosed structure that is used to grow plants under protected conditions. Greenhouses (also known as glasshouses) are transparent, enclosed, climate-controlled structures (Fig. 1) in which young, tender, or out-of-season plants…

A plant, Psidium guajava, of tropical American origin that has long been in cultivation and that produces an edible, aromatic, sweet, juicy fruit. The guava plant is a shrub or low tree that belongs to the myrtle family (Myrtaceae). The fruit (see…

A desert plant, Parthenium argentatum, cultivated as a source of rubber. Guayule belongs to the aster family (Asteraceae). It is a native perennial shrub that grows in the Chihuahuan Desert of north-central Mexico and southwestern Texas. The plant…

A medium-sized to large tree, Celtis occidentalis. The hackberry tree (Celtis occidentalis; see illustration), also known as the common hackberry, is a member of the order Rosales and occurs in the eastern half of the United States, except the…

The human brain is a bilaterally symmetrical structure which is for the most part richly interconnected by two main bridges of neurons called the corpus callosum and anterior commissure. These structures can be surgically sectioned in humans in an…

The genus Tsuga of the pine family, characterized by flattened needles with two white lines beneath the needlelike leaves, which have distinct short stalks. The cones of hemlock are small and pendent (see illustration). Eastern hemlock (Tsuga…

The fiber and the plant Cannabis sativa. The hemp plant, Cannabis sativa (see illustration), is a member of the flowering plant family Cannabaceae in the order Rosales. The fiber from hemp plants has long been used as a source of industrial fiber.…

An agave plant, Agave fourcroydes, and the fiber obtained from its leaves. Henequen is produced only in Mexico, Cuba, and El Salvador. It is a hard plant fiber and is used to make rope, twine, and cord. Henequen is sometimes incorrectly called…

Any species of the genus Carya, formerly known botanically as Hicoria. Hickories are mostly tall forest trees characterized by strong, terminal, scaly winter buds; pinnately compound leaves (see illustration); solid piths (not chambered); and fruit…

Any species of the genus Ilex. The American species of holly (Ilex opaca) attains a maximum height of 40–50 ft (12–15 m) and has evergreen leaves. American holly grows naturally in the eastern and southeastern United States, close to the Atlantic…

A plant, Humulus lupulus, belonging to the family Cannabaceae. The hop plant is a rough-stemmed, tall-twining dioecious perennial herb and belongs to the same family as hemp and hackberries. It is propagated by cuttings of underground stems. The…

Any tree of the genus Ostrya of the birch family. Hophornbeam is represented in North America by two species, O. virginiana and O. knowltonii. Ostrya virginiana (American or eastern hophornbeam) is a small tree that may reach a height of 60 ft (18…