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cactus

(Encyclopedia)cactus, any plant of the family Cactaceae, a large group of succulents found almost entirely in the New World. A cactus plant is conspicuous for its fleshy green stem, which performs the functions of ...

vineyard

(Encyclopedia)vineyard, land on which cultivation of the grape—known as viticulture—takes place. As many as 40 varieties of grape, Vitis vinifera, are known. The few that grow wild are generally not used; all d...

climate

(Encyclopedia)climate, average condition of the atmosphere near the earth's surface over a long period of time, taking into account temperature, precipitation (see rain), humidity, wind, barometric pressure, and ot...

malaria

(Encyclopedia)malaria, infectious parasitic disease that can be either acute or chronic and is frequently recurrent. Malaria is common in Africa, Central and South America, the Mediterranean countries, Asia, and ma...

silk

(Encyclopedia)silk, fine, horny, translucent, yellowish fiber produced by the silkworm in making its cocoon and covered with sericin, a protein. Many varieties of silk-spinning worms and insects are known, but the ...

orchid

(Encyclopedia)CE5 Rose pogonia, Pogonia ophioglossoides, a member of the orchid family orchid, popular name for members of the Orchidaceae, a family of perennial herbs widely distributed in both hemispheres. Th...

Chordata

(Encyclopedia)CE5 Common features in representative groups of the phylum Chordata Chordata kôrdāˈtə, –däˈ– [key], phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal ...

Annelida

(Encyclopedia)CE5 A. The earthworm, Lumbricus terrestris, representative of the phylum Annelida. B. Internal anatomy of an earthworm. Annelida ənĕlˈĭdə [key] [Lat., anellus=a ring], phylum of soft-bodied, ...

Platyhelminthes

(Encyclopedia)CE5 A. Planaria, representative of the phylum Platyhelminthes B. Internal anatomy of Planaria Platyhelminthes plătˌēhĕlmĭnˈthēz [key], phylum containing about 20,000 species of soft-bodied,...

mass extinction

(Encyclopedia)mass extinction, the extinction of a large percentage of the earth's species, opening ecological niches for other species to fill. There have been at least ten such events. The five greatest were thos...