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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.…

A major plant hormone that plays an important role in plant growth and development. Abscisic acid (ABA), with a chemical formula of C15H20O4 (Fig. 1), is one of the most significant hormones found in plants. It is responsible for regulating various…

Any of a class of plant growth substances (phytohormones or plant hormones) that have an essential role in coordination of many growth and developmental processes during the life cycle of plants, especially the ability to increase the rate of shoot…

A class of nonflagellate unicellular algae, commonly called diatoms, with boxlike silicified walls. Members of the algal class Bacillariophyceae are commonly termed diatoms (Fig. 1). Diatoms range in maximum dimension from 4 μm (0.00004 in.) to more…

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,…

Fungi that exhibit the natural phenomenon of bioluminescence (the ability of an organism to emit visible light). Bioluminescence is the emission of photons of visible light by living organisms via the chemical reaction of molecular oxygen (O2) with…

The branch of biological science that embraces the study of plants and plant life. Botany is the scientific study of plants (see illustration), encompassing investigations of plant anatomy, physiology, genetics, phylogeny, ecology, pathology, and…

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…

Any living or fossil member of the plant division Pinophyta, consisting chiefly of woody trees or shrubs that produce cones and evergreen needles. Conifers are predominantly cone-bearing, evergreen trees and shrubs belonging to the order Pinales, as…

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…

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…

A former order of rosid flowering plants, division Magnoliophyta (Angiospermae), in the class Magnoliopsida (dicotyledons). The order Euphorbiales consisted of the large family Euphorbiaceae (with about 7500 species) and 3 small satellite families…

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…

Hypersensitivities or altered reactivities caused by fungal allergens. More than 20% of the population in industrialized countries suffers from allergic disease, and diverse allergens (substances foreign to the body that cause allergy) associated…

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…

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…

Members of a family of diterpenoid carboxylic acids that are notable for being plant hormones. Gibberellins are diterpenoid carboxylic acids. Most of them possess ent-gibberellane or ent-20-norgibberellane carbon (C) skeletons. Gibberellins occur in…

A class of lower green plants called liverworts that belong to the division Bryophyta. The class Hepaticopsida, also called Marchantiopsida, comprises the liverworts, which are nonvascular land plants. Although there is a great diversity of external…

A tentative supposition with regard to an unknown state of affairs, the truth of which is thereupon subject to investigation by any available method, either by logical deduction of consequences which may be checked against what is known, or by…

The diverse totality of microorganisms regularly found on and in the human body is collectively referred to as the human microbiota or microbial flora, with the largest microbial community in the body residing in the large intestine, or colon.…

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…

The body of knowledge that concerns the fundamental nature, function, development, and use of formal models in science and technology. In its most general sense, a model is a proxy. A model is one entity used to represent some other entity for some…

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…

An order of flowering plants that have previously been included in the subclass Magnoliidae. Deoxyribonucleic acid (DNA) sequence studies have demonstrated that Nymphaeales as previously defined contain two families, Ceratophyllaceae (water…

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…

An order of filamentous freshwater green algae (Chlorophyceae) with unique morphological features including (1) an elaborate method of cell division that results in the accumulation of apical caps, (2) zoospores and antherozoids with a subapical…

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…

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…

Any member of the plant family Orchidaceae, having complex, specialized irregular flowers usually with only one or two stamens. The orchid family, Orchidaceae, is among the largest families of plants and is estimated to contain more than 25,000…

An order of flowering plants, division Magnoliophyta (Angiospermae), in the order Asparagales (monocotyledons). The order Orchidales consists of four families: the Orchidaceae, with 20,000–25,000 species; the Burmanniaceae, with more than 100…

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…

An order of flowering plants (angiosperms) in the eurosid I group of the rosid dicots. The order is previously unrecognized in classifications of the angiosperms, but is indicated by numerous studies of DNA sequences. Oxalidales consist of five…

An order of monocotyledons, the composition of which only recently has been revealed by deoxyribonucleic acid (DNA) sequence studies of four genes. Included are four families, two of which have been generally viewed as closely related: Pandanaceae…

An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Magnoliidae of the class Magnoliopsida (dicotyledons). The order Papaverales consists of two families: Papaveraceae, with approximately 200 species; and…

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…