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A plant, Musa textilis, of the banana family that is valuable for its hard fiber (also known as Manila hemp). Abaca (Musa textilis) is a flowering plant native to the Philippines and Borneo. Taxonomically, it is assigned to the order Zingiberales.…

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…

A type of sweet or sour fruit of the Prunus genus, as well as the tree that bears the fruit. Cherry trees belong to the Prunus genus in the order Rosales, and the sweet and sour fruits of these trees are called cherries (Fig. 1). There are…

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…

A fiber obtained from the cotton plant Gossypium. The cotton plant (genus Gossypium, order Malvales; Fig. 1) has been used by humans for more than 5000 years. The fiber (cotton) obtained from this plant is the most widely used natural fiber because…

Impairment of the ability to read. Developmental dyslexia, which is a learning disorder with a neurobiological basis, is characterized by unexpected difficulty in reading in children and adults who otherwise possess the intelligence and motivation…

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…

Soil ingestion by animals. Grazing animals such as sheep and cattle ingest varying amounts of soil when they graze herbage contaminated with it.Pastures become contaminated with soil when livestock walk across the herbage, particularly in wet…

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…

Citrus limon, a small evergreen tree belonging to the order Sapindales that is cultivated for its fruit. In commercial terms, the lemon (Citrus limon; order Sapindales) is the most important of the acid citrus fruits (see illustration). It probably…

Lama glama, a member of the camel family (Camelidae) found only in South America. The llama (see illustration) is an artiodactyl, or even-toed ungulate, belonging to the mammalian family Camelidae. It has two toes on each foot. The llama is a…

Trees that can convert (fix) atmospheric nitrogen into a form that can be utilized for growth. The ability to convert (fix) atmospheric nitrogen into a form that can be used for plant growth is confined to bacteria and cyanobacteria. Plants fix…

A delicately flavored spice obtained from the nutmeg tree (Myristica fragrans), a native of the Moluccas (Maluku Islands or Spice Islands). The nutmeg tree is a dark-leafed evergreen that can reach 9–18 m (30–60 ft) in height and is a member of the…

A genus (Quercus) of trees, some of which are shrubby, with about 200 species, mainly in the Northern Hemisphere. About 50 species of oaks are native in the United States. All oaks have scaly winter buds, usually clustered at the ends of the twigs,…

An agricultural crop of the genus Avena grown for its grain and straw in most countries of the temperate zones of the world. Oats (Fig. 1) belong to the order Poales (Cyperales), family Poaceae (Gramineae), and genus Avena. The most important crop…

A warm-season annual, Hibiscus esculentus (also Abelmoschus esculentus), of Ethiopian origin. Okra, also called gumbo, is grown for its immature pods (see illustration), which are used generally in the preparation of soups, but are also eaten as a…

One of the chemical senses, specifically the sense of smell. Olfaction comprises the action or capacity of smelling, and is a form of chemoreception (the ability of organisms to detect changes in the chemical composition of their exterior or…

Any plant of the genus Olea in the order Lamiales (alternatively Scrophulariales), especially O. europaea, which is cultivated for its drupaceous fruit. Olea europaea is a small to medium-sized evergreen tree (Fig. 1). Olive fruits, both ripe…

A cool-season biennial, Allium cepa, that is cultivated for its edible bulb. The onion is of Asiatic origin and belongs to the plant order Asparagales; it was formerly included in the order Liliales. Related species are leek (A. porrum), garlic (A.…

Any of various evergreen trees of the genus Citrus, cultivated for its edible fruit. Orange trees (genus Citrus) belong to the family Rutaceae of the order Sapindales. The various trees classified as orange trees are most notable for producing…

An herb, also known as wild marjoram. The dried leaves of several species of aromatic plants are known as oregano; thus, oregano is a common name for a general flavor and aroma rather than the name of a specific plant. MarjoramEuropean oregano…

The genus Maclura of the mulberry family, with one species, M. pomifera. The osage orange tree may attain a height of 60 ft (18 m) and has yellowish bark, milky sap, simple entire leaves, strong axillary thorns, and aggregate green fruit that are…

Carica papaya, a semiwoody, usually single-stemmed, herbaceous plant cultivated for its fruit in tropical and subtropical regions. The papaya plant (Fig. 1) originated along the Caribbean lowlands of Mesoamerica and is now extensively and…

A type of pepper, Capsicum annuum, with nonpungent flesh, grown for its long red fruit. The paprika pepper (see illustration) is a member of the plant order Solanales (formerly assigned to Polemoniales) and is of American origin. It is most popular…

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…

A deciduous fruit tree species, Prunus persica, of the order Rosales. The peach (see illustration), taxonomically known as Prunus persica (order Rosales), is a notable fruit tree species that originated and was first cultivated in western China. It…

A long-season cultivar (cultivated variety) of muskmelon, Cucumis melo, of the gourd family. Persian melons (see illustration) are members of the family Cucurbitaceae (which includes melons, squashes, pumpkins, and cucumbers) in the order…

A deciduous fruit tree species, Diospyros kaki, in the ebony family (Ebenaceae). Persimmon trees (Fig. 1) originated in the subtropical regions of China, but were cultivated more extensively in Japan. At the present time, China, South Korea, and…

A type of pepper, Capsicum annuum, grown for its thick, sweet-fleshed red fruit. The pimento (see illustration) is a member of the plant order Solanales (formerly assigned to Polemoniales) and is of American origin. The pimento gets its name from…

A fiber, also known as pineapple fiber, obtained from the large leaves of the pineapple plant grown in tropical countries. Piña (also spelled pina) is a natural fiber (see illustration) that is white and especially soft and lustrous. In the…

Any tree of the genus Pinus, of the family Pinaceae, characterized by evergreen leaves, usually in tight clusters (fascicles) of two to five, rarely single. There are about 80 known species of pine distributed throughout the Northern Hemisphere.…

The edible seed of more than a dozen species of evergreen cone-bearing trees in the genus Pinus, native to the temperate zone of the Northern Hemisphere. The important pine nut–producing species are the stone pine (P. pinea) of southern Europe; the…

A low-growing perennial plant (genus Ananas) and its edible fruit, indigenous to the Americas. The cultivated varieties (cultivars) of pineapple belong to the species Ananas comosus (alternatively Ananas sativus) of the plant order Bromeliales or…

A small, spreading dioecious evergreen tree, Pistacia vera, of the Anacardiaceae family (order Sapindales), with leaves that have three to five broad leaflets and with large drupaceous fruit containing an edible seed (nut). The pistachio tree is…

The psychological property of sound characterized by highness or lowness. Pitch is one of the two major auditory attributes of simple sounds, the other being loudness. Simple and complex sounds A simple sound source, such as a tuning fork, produces…

Any of various smooth-skinned stone fruits grown on shrubs or small trees (genus Prunus, order Rosales). Plums are widely distributed in all land areas of the North Temperate Zone, where many species and varieties are adapted to different climatic…