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fern

(Encyclopedia)CE5 Life cycle of a fern fern, any plant of the division Polypodiophyta. Fern species, numbering several thousand, are found throughout the world but are especially abundant in tropical rain fores...

eutrophication

(Encyclopedia)eutrophication yo͞otrōˌfĭkāˈshən [key], aging of a lake by biological enrichment of its water. In a young lake the water is cold and clear, supporting little life. With time, streams draining i...

milkweed

(Encyclopedia)milkweed, common name for members of the Asclepiadaceae, a family of mostly perennial herbs and shrubs characterized by milky sap, a tuft of silky hairs attached to the seed (for wind distribution), a...

supersymmetry

(Encyclopedia)supersymmetry, in physics, theory concerning the relationship of the elementary particles called boson to those known as fermions, and vice versa, and linking the four fundamental forces. In supersymm...

peyote

(Encyclopedia)peyote pāōˈtē [key], spineless cactus (Lophophora williamsii), ingested by indigenous people in Mexico and the United States to produce visions. The plant is native to the SW United States, partic...

Germanic languages

(Encyclopedia)Germanic languages, subfamily of the Indo-European family of languages, spoken by about 470 million people in many parts of the world, but chiefly in Europe and the Western Hemisphere. All the modern ...

gnat

(Encyclopedia)gnat, common name for any one of a number of small, fragile-looking two-winged flies of the suborder Nematocera, order Diptera, which includes the families Tipulidae (crane flies), Bibionidae (hairfli...

mental hygiene

(Encyclopedia)mental hygiene, the science of promoting mental health and preventing mental illness through the application of psychiatry and psychology. A more commonly used term today is mental health. In 1908, th...

Paiute

(Encyclopedia)Paiute pīo͞otˈ [key], two distinct groups of Native North Americans speaking languages belonging to the Shoshonean group of the Uto-Aztecan branch of the Aztec-Tanoan linguistic stock (see Native A...

Sulu Archipelago

(Encyclopedia)Sulu Archipelago so͞oˈlo͞o [key], island group, 1,086 sq mi (2,813 sq km), the Philippines, SW of Mindanao. Lying between the Celebes and Sulu seas, it includes over 900 volcanic islands and coral ...