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cultivation

(Encyclopedia)cultivation, tilling or manipulation of the soil, done primarily to eliminate weeds that compete with crops for water and nutrients. Cultivation may be used in crusted soils to increase soil aeration ...

mandrake

(Encyclopedia)mandrake, plant of the family Solanaceae (nightshade family), the source of a narcotic much used during the Middle Ages as a pain-killer and perhaps the subject of more superstition than any other pla...

exponent

(Encyclopedia)exponent, in mathematics, a number, letter, or algebraic expression written above and to the right of another number, letter, or expression called the base. In the expressions x2 and xn, the number 2 ...

ginger

(Encyclopedia)ginger, common name for members of the Zingiberaceae, a family of tropical and subtropical perennial herbs, chiefly of Indomalaysia. The aromatic oils of many are used in making condiments, perfumes, ...

meristem

(Encyclopedia)meristem mĕrˈistĕmˌ [key], a specialized section of plant tissue characterized by cell division and growth. Much of the mature plant's growth is provided by meristems. Apical meristems found at th...

pi

(Encyclopedia)pi, in mathematics, the ratio of the circumference of a circle to its diameter. The symbol for pi is π. The ratio is the same for all circles and is approximately 3.1416. It is of great importance in...

Diefenbaker, John George

(Encyclopedia)Diefenbaker, John George dēˈfənbāˌkər [key], 1895–1979, Canadian political leader. Elected to Parliament (1940), he succeeded George Drew as leader of the Progressive Conservative party (1956)...

Dillon, John Forrest

(Encyclopedia)Dillon, John Forrest, 1831–1914, American jurist, b. Montgomery co., N.Y., M.D. State Univ. of Iowa, 1850. He abandoned medical practice early in his career and was admitted to the Iowa bar in 1852....

Dyson, Freeman John

(Encyclopedia)Dyson, Freeman John dīˈsən [key], 1923–2020, British-American theoretical physicist and mathematician, studied Trinity College, Cambridge (B.A., 1945) and Cornell. He did bomber operations resear...

Eaton, John Henry

(Encyclopedia)Eaton, John Henry, 1790–1856, U.S. Senator (1818–29) and Secretary of War (1829–31), b. Halifax co., N.C. After being admitted to the bar, he practiced in Franklin, Tenn., and married Myra Lewis...