Igneous rock (derived from the Latin word ignis meaning fire) is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava. Igneous rock may form with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. This magma can be derived from partial melts of pre-existing rocks in either a planet's mantle or crust. Typically, the me..
Toxicodendron is a genus of in the sumac family, Anacardiaceae. It contains woody , and , including poison ivy, poison oak, and the lacquer tree. All members of the genus produce the skin-irritating oil urushiol, which can cause a severe allergic reaction. The generic name is derived from the Greek words ( toxikos), meaning "poison," and ( dendron), meaning "tree". ξ1 The best known members of the genus in North America are poison ivy (T. radicans), practically ubiquitous throughout most of eastern..
