Oxalis

oxalis (ŏk`səlĭs) or wood sorrel, any species of the plant genus Oxalis. Most of the cultivated kinds are tropical herbs used as window plants. The leaves are usually cloverlike and respond to darkness with "sleep" movements by folding back their leaflets. Several species grow wild in North America, including the white wood sorrel (O. acetosella), widely distributed in the north temperate zone and one of the plants identified as the shamrock. This and, to a lesser extent, other species have long been used for salads and greens because of their pleasantly acid taste; these species contain oxalic acid. O. tuberosa has a starchy tuber that has been valued in the high Andes for centuries. Although species of Oxalis are called sorrels, the genus is unrelated to the true sorrel, or dock (genus Rumex), of the buckwheat family. Oxalis is classified in the division Magnoliophyta, class Magnoliopsida, order Geramales, family Oxalidaceae.

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oxalis

Any of about 850 species of small herbaceous plants that make up the genus Oxalis, native mostly to southern Africa and tropical and South America. Most members are familiar garden ornamentals. The name (Greek for “acid”) reflects the plant's sharp acidic taste. The common wood sorrel (O. acetosella) of eastern North America and Britain is a small, stemless plant with cloverlike three-part leaves, whose leaflets fold back and droop at night. The flowers have five white, purple-veined petals. After the fruit splits open, the fleshy coat of the seed curls back elastically, ejecting the true seed.

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Oxalis 

a genus of plants of the family Oxalidaceae. They are perennial and, less frequently, annual herbs; some are subshrubs. The leaves are alternate and usually ternately or palmately compound. The flowers are pentamerous; the fruit is a capsule. There are approximately 800 species, distributed primarily in Southern Africa, South America, and Mexico. Six species are found in the USSR. The European wood sorrel, or sheep sorrel (Oxalis acetosella), which is often found in shady coniferous forests, is a small stemless plant with a creeping rhizome. The trifoliate bracts fold up at night and in overcast weather. The flowers, which are solitary, are white with pinkish violet veins. The leaves of the European wood sorrel, like those of the procumbent yellow sorrel (O. corniculata), contain vitamin C and oxalic acid; they are toxic to sheep when consumed in large quantities. Some African and American species are cultivated in a number of countries for their edible tubers. Many species are cultivated as ornamentals.