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It is estimated that 1 gram of soil can be inhabited by up to 109 microorganisms and approximately 60,000 bacterial species. Moreover, soil harbors a vast reservoir of antimicrobial agents, and soil-dwelling bacteria have played a key role in the…

Biocontrol, or biological control, is the natural or applied regulation of populations of pest organisms—especially insects—through the role or use of natural enemies. In other words, biocontrol uses living organisms to reduce and eliminate pest…

The biotechnology used in the creation of genetically modified crops is being expanded to encompass the bioengineering of plants that contain therapeutically important proteins and molecules that can be utilized in the manufacturing of…

Materials added to the soil, or applied directly to crop foliage, to supply elements needed for plant nutrition. These materials may be in the form of solids, semisolids, slurry suspensions, pure liquids, aqueous solutions, or gases.The chemical…

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 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…

Bananas (Musa genus) are one of the world's most valuable and popular primary agricultural commodities. However, the most prevalent naturally occurring bananas, that is, those of the Cavendish variety, are being severely decimated by Panama disease…

Global climate change affects all areas of the Earth, with some regions experiencing greater impacts than others. In particular, the Arctic treeline—that is, the southern limit of the Arctic Bioclimate Zone—is being affected to various degrees by…

Forests absorb and store carbon. If this ability is hampered, then levels of atmospheric carbon will increase and global temperatures will rise, leading to potentially drastic climatic changes. In particular, deforestation (the permanent elimination…

Tiny granules found within the pollen sacs of numerous species of flowers may play a key role in allergic reactions associated with pollen. Measuring less than 4 micrometers (μm) in diameter (most being less than 1 μm), these granules are called…

A plant cell in which the cell wall has been removed. Although the plant cell is the basic unit of structure and function in plants, the term protoplast has been used to describe the organized entity of the living components of the plant cell that…

Loss in the quality or productivity of soil that is often the result of human activities, such as agriculture practices, deforestation, mining, waste disposal, and chemical spills. Soil degradation is attributed to changes in soil nutrient status,…

New regulations by the U.S. Food and Drug Administration (FDA) that went into effect on January 1, 2017, banned the use of antibiotics as feed supplements to help livestock and poultry grow faster. The new rules, prohibiting the over-the-counter…

Because of nutrient-poor soil and the high cost of fertilizer, farmers in parts of Africa often produce only one-fifth to one-tenth as much corn (maize) per hectare as farmers in the United States do. Over time, farming in Africa and elsewhere in…

Wildfires are known to emit large amounts of gaseous and particulate pollutants. In an effort to identify and quantify these pollutants, researchers took their instruments to the skies where they sampled and analyzed smoke plumes from aircraft…

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…

An informal assemblage of predominantly aquatic organisms that carry out oxygen-evolving photosynthesis, but lack specialized water-conducting and food-conducting tissues. Algae (Fig. 1) may be either prokaryotic organisms (lacking an organized…

A natural process in which harmful or beneficial effects are caused by secondary metabolites that spread from a donor organism to a recipient and are produced by plants, algae, bacteria, and fungi. Allelopathy is a key ecological process and has…

Many trees enjoy extremely long lives in comparison to humans and other animals. Yet one group of trees, the bristlecone pines, stands out as the most ancient of all, with individual trees that commonly live for thousands of years, including one…

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…

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…

An order of flowering plants in the core eudicots. The order Malvales consists of 10 families and approximately 6000 species. The circumscription of the order has been altered greatly in recent years, largely on the basis of deoxyribonucleic acid…

A material useful for the mitigation, control, or elimination of plants or animals detrimental to human health or economy. Pesticides are formulated products that contain both active and inert ingredients. The active ingredients are the effective…

Between 2004 and 2014, the total phosphorus content of lakes and streams in the contiguous (lower 48) United States rose, according to surveys by the U.S. Environmental Protection Agency (EPA) reported in the journal Environmental Science &…

The relationships between plants and water, including the hydration of plant cells and the transport of water within a plant. Water is the most abundant constituent of all physiologically active plant cells. Leaves, for example, have water contents…

A former order of flowering plants, division Magnoliophyta (Angiospermae) of the class Magnoliopsida (dicotyledons), reassigned to the suborder Polygonineae in the order Caryophyllales. The order Polygonales was considered as an ordinal grouping in…

Biochar is charcoal made from biomass (organic matter used for energy). A process called pyrolysis, in which biomass is heated to high temperature in the absence of oxygen, produces biochar along with combustible gases (syngas) and oils (bio-oils).…

An herbaceous perennial, Rheum rhabarbarum or Rheum rhaponticum, of Mediterranean origin, belonging to the plant order Polygonales in older botanical classifications or Caryophyllales in newer classifications. Rhubarb (Rheum rhabarbarum or Rheum…

Concrete and steel have been the materials of choice for constructing high-rise buildings for over 100 years. Definitions of high-rise buildings vary, but according to the U.S. National Fire Protection Association high-rise buildings are 23 meters…

A rare animal, Vicugna vicugna, the smallest member of the family Camelidae, whose fiber is strong, resilient, and elastic, with exquisite fineness and beauty. The vicuna, or vicuña (see illustration), belongs to the family Camelidae in the…

An artificial leaf is a solar cell that uses water and an electrical current generated from sunlight to produce hydrogen (for fuel) and oxygen. It is currently in development at laboratories worldwide. If successful, the artificial leaf could serve…

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 medium-sized, spreading evergreen tree (Anacardium occidentale), native to Brazil, which is grown widely in the tropics for its kidney-shaped edible nuts and the resinous oil in the shells. Cashews belong to the family Anacardiaceae in the order…

Any member of the grass family (Poaceae or Gramineae) that produces edible grains usable as food by humans and livestock. Common cereals include rice, wheat, barley, oats, maize (corn), sorghum, rye, and certain millets. Triticale is a cereal…

A class of branched, filamentous green algae (division Charophyta), collectively known as the stoneworts, brittleworts, or muskgrasses, which occur mostly in freshwater or brackish-water habitats. Members of the class Charophyceae (often referred…

A perennial herb, Cichorium intybus, with a long taproot; a coarse, branching stem; and a basal rosette of numerous leaves. Chicory (see illustration) is a member of the Asteraceae (Compositae) family with a history of cultivation dating back to…

A highly diversified division of the plant kingdom comprising green algae that have chlorophyll a and chlorophyll b as the predominating pigments; also known as Chlorophyta or Chlorophycophyta. Members of the division Chlorophycota (also referred…

A devastating bacterial infection of citrus trees, also known as huanglongbing or yellow dragon disease, transmitted by psyllids (jumping plant lice). Citrus greening disease, which was first reported in Asia during the late 1800s, is the most…

A common name used loosely to designate the true clovers, sweet clovers, and other members of the plant family Fabaceae (Leguminosae). This article discusses true clovers (genus Trifolium), sweet clovers (genus Melilotus), and clover diseases. True…

The major alkaloid obtained from the seed capsules, corms, and bulbs of the meadow saffron (autumn crocus; Colchicum autumnale). Colchicine is a fairly abundant alkaloid in the dried corms (fleshy underground stems) [0.3–0.8%] and seeds (0.6–0.9%)…

Conifers are predominantly cone-bearing, evergreen trees and shrubs belonging to the order Pinales, as well as a small number of extinct orders, in the class Pinopsida of the division Pinophyta (Coniferophyta). All are woody plants, and they are…

An order of red algae, commonly called coralline algae. The order Corallinales (class Rhodophyceae; phylum or division Rhodophyta) consists of three families: Corallinaceae, Hapalidiaceae, and Sporolithaceae. Coralline algae (see illustration) are…

Unharvested crops grown to improve soil quality or enhance pest management. Increasing numbers of farmers plant cover crops as a means of conserving soil, enhancing production, and reducing off-farm inputs. The sustainable agriculture movement has…

Much of coastal and southern California has a Mediterranean climate, which is characterized by cooler, wetter winters and hotter, drier summers. Only drought-resistant plant species can survive without irrigation in this type of climate. Turf…

Plants grown and harvested for food, feed, or industrial purposes. Farm crops may be roughly classified as follows: (1) food crops—the bread grains [wheat (see illustration) and rye], rice, sugar crops (sugarbeets and sugarcane), potatoes, and dry…

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,…

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…

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 biflagellate water molds, downy mildews, and other microorganisms classified as members of the Oomycota (also termed Oomycetes) have long puzzled taxonomists. Previously, investigators thought them to constitute a group within the true fungi…

Two varieties of apples that have been genetically engineered not to turn brown when cut or bruised were cleared in February and March of 2015 for growth and sale in Canada by the Canadian Food Inspection Agency (CFIA) and Health Canada (HC) and in…

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,…

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,…

Intensively managed plants cultivated for food or for esthetic purposes. Plant agriculture is divided traditionally into the fields of agronomy (herbaceous field crops, mainly grains, forages, oilseeds, and fiber crops), forestry (forest trees and…

The use of certain insects to attack and destroy pests—predominantly other insects—is an intriguing and increasingly popular natural method of biological insect control. In particular, the ichneumon wasp is employed for this purpose to control pest…

Grasses that were once almost exclusively for pasture and meadow and now furnish ground cover for lawns, sports fields, industrial parks, and roadsides. Lawn and turf grasses have functional and esthetic purposes. The acreage of mowed turf grass…

A widely used cloth made from flax fibers. Linen is noted for its evenness of thread, fineness, and density. Its uses include garments, tablecloths, sheeting, towels, and thread.The flax plant (Linum usitatissimum) that supplies the fiber needs a…

The hard-shelled seed obtained from the fruit of a tropical evergreen tree, genus Macadamia, native to Queensland and New South Wales in Australia. Macadamia trees grow to 15 m (49 ft) in height and have a dense foliage of glossy, leathery leaves.…

The cultivation of plants, primarily trees, that produce nuts. The term nut is used loosely. In general, a nut is defined as any edible fruit or seed enclosed in a hard shell. Botanically, a nut is a hard, indehiscent, one-seeded (nut), pericarp…

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…

The olive tree (Olea europaea) is an ancient cultivated plant that was originally domesticated by early civilizations in the eastern Mediterranean regions. Today, the major olive-producing countries are Spain, Italy, Greece, and Turkey, which…

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…

The largest order of modern ferns, commonly called the true ferns; also known as Filicales. The order Polypodiales contains approximately 250 genera and 9500 species. Although members of the Polypodiales are well represented in the temperate…

Chenopodium quinoa, an indigenous pseudocereal of the Andean region of South America. Quinoa (Fig. 1) was one of the first plants to be domesticated in South America, and it is now recognized agronomically as an important crop. It has received…

An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Magnoliidae of the class Magnoliopsida (dicotyledons). The order Ranunculales consists of 7 or 8 families and about 3200–4500 species, depending on the…

An annual cereal grass plant, Oryza sativa (family Poaceae), cultivated for its carbohydrate-rich grain. Rice is the major source of food for nearly one-half of the world's population. In China, Japan, Korea, the Philippines, India, and other…

An order, now discontinued, of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Asteridae of the class Magnoliopsida (dicotyledons). The order Rubiales has been abandoned in modern plant classification schemes, and its…

A winter-hardy and drought-resistant cereal plant, Secale cereale, belonging to the grass family [Poaceae (Gramineae)], that is cultivated for its grain. Rye (Fig. 1) resembles wheat, with which it intercrosses to a limited extent. Rye is…

The plant Crocus sativus, which is a member of the iris family (Iridaceae) in the order Asparagales, and the spice derived from it. Originally a native of Greece and Asia Minor, saffron is now cultivated in various parts of Europe, India, and…

Members of the genus Ovis in the family Bovidae [order Artiodactyla (the even-toed, hoofed mammals)]. Sheep were possibly the first animals to be domesticated about 11,000 years ago in southwestern Asia. At that time, they were closely associated…

The lustrous protein fiber produced by silkworms (larvae of the silkworm moth); also the thread or cloth made from such fiber. Silk is a highly prized commodity by the consumer, even though certain manufactured fabrics now have some qualities that…

A genus of extinct calcareous red algae (Rhodophyta). The extinct algal members of the genus Solenopora (family Solenoporaceae, order Corallinales, division Rhodophyta) are characterized by encrusting, rounded, nodular growth forms ranging in size…

Any of a variety of widely cultivated grasses, especially Sorghum bicolor, grown for grain and herbage. Sorghum (Fig. 1) includes many widely grown grasses having a variety of names. Sorghum is known as guinea corn in West Africa, kafir corn in…

Glycine max, an erect annual legume native to China that is widely cultivated for forage and for its seed, which is a major source of vegetable protein and oil for human and animal consumption and for industrial usage. Introduced from China into…

St. John's wort [Hypericum perforatum L. (Hypericaceae)] is a perennial plant (see illustration) and one of the best-known and best-researched Western medicinal plants. It has been used for millennia as a result of its many medicinal properties; for…

Crops produced as major sources of sugar, syrup, and other sugar substances. Sugar crops include sugarbeet (also spelled sugar beet), sugarcane, sweet sorghum, sugar maple, sugar palm, honey, corn, and chicory. Sugar is a broad term applied to a…

The science of breeding, raising, and marketing swine. Any domesticated member of the genus Sus in the family Suidae is known as a swine (also hog or pig) [Fig. 1]. The agricultural enterprise of swine production is usually located in proximity to…

An order of ascolichens (class Lecanoromycetes, division Ascomycota) characterized by an unusual apothecium. Members of the order Teloschistales (formerly Caliciales) are ascolichens, that is, lichens [symbiotic associations of fungi (mycobionts)…

An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Dilleniidae of the class Magnoliopsida (dicotyledons). The order Theales consists of about 17 families and more than 3500 species. The largest families include…

Any plant of the genus Nicotiana cultivated for its leaves, and the dried leaves of the plant. Most often, tobacco means a leaf product derived from the plant genus Nicotiana containing 1–3% of the alkaloid nicotine, which produces a narcotic…

Pathological conditions affecting shade and forest trees. Diseases of both shade and forest trees are caused by the same pathogens, but the trees differ in value, aesthetics, and utility. In forests, disease is significant only when large numbers…

The common name for fern plants primarily belonging to the families Cyatheaceae and Dicksoniaceae, whose members typically develop tall trunks crowned with leaves (fronds). Tree ferns exhibit a treelike (arborescent) habit (Fig. 1), often reaching…

The common name applied to about a dozen species of large deciduous trees in the genus Juglans, and the edible nut of these trees. Walnut trees are widely distributed over temperate North America and South America, southeastern Europe, and central…

A textile fiber made of the soft undercoat of sheep and various other animals, including angoras, goats, camels, alpacas, llamas, and vicunas. Wool is the most widely used animal fiber in the world. In addition, wool provides warmth and physical…

All buildings used on the farm for housing livestock and the farm family and for storing grain, livestock feed, and farm machinery. In the United States, today's farms are larger, more specialized, and more mechanized than those of the past, and…

A branch of meteorology that examines the effects and impacts of weather and climate on crops, rangeland, livestock, and various agricultural operations. The branch of agricultural meteorology dealing with atmospheric-biospheric processes occurring…

Few fossils of early flowering plants (angiosperms; Magnoliophyta) have been found. The group appears suddenly in the fossil record and quickly rose to ecological dominance. As a result, Charles Darwin famously referred to the origin of angiosperms…

An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Arecidae of the class Liliopsida (monocotyledons). The order Arales consists of two families: Araceae, with about 1800 species; and Lemnaceae, with only about 30…

An area set aside for the cultivation of trees and shrubs for educational and scientific purposes. An arboretum differs from a botanical garden because the former emphasizes woody plants; in contrast, a botanical garden includes investigation of the…

A branch of horticulture concerned with the selection, planting, and care of woody perennial plants. Knowing the potential form and size of plants is essential to effective landscape planning as well as to the care needed for plants. Arborists are…

A tree or shrub, sometimes called the tree of life, belonging to the genus Thuja of the order Pinales. Arborvitae is characterized by flattened branchlets with two types of scalelike leaves. At the edges of the branchlets, the leaves may be keeled…

An order of flowering plants, division Magnoliophyta (Angiospermae), of the subclass Arecidae in the class Liliopsida (monocotyledons). The name of the subclass is derived from the ordinal name. The order consists of the single family Arecaceae…

A subclass of the class Liliopsida (monocotyledons) of the division Magnoliophyta (Angiospermae), the flowering plants, consisting of four orders (Arecales, Cyclanthales, Pandanales, and Arales), five families, and nearly 6000 species. Except for…

An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Magnoliidae of the class Magnoliopsida (dicotyledons). It contains only the family Aristolochiaceae, with 8 or 10 genera and about 600 species, most of them in…

Cynara scolymus (alternatively Cynara cardunculus var. scolymus), a herbaceous perennial plant, in the family Compositae (order Asterales), whose flower head is edible. The artichoke, also called the globe artichoke, has its origin in the…