oxalis

oxalis 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.

Oxalis (family Oxalidaceae) A genus of annual or perennial herbs that have alternate, palmate leaves without stipules. There are 1 to many leaflets. The flowers are regular, bisexual, and usually solitary, with 5 free and persistent sepals and 5 petals, often fused at the base. There are 10 stamens. The superior ovary is composed of 5 fused carpels, each with a separate style. The fruit is a capsule. Oxalis species are known for their characteristically clover-like leaves (e.g. O. acetosella, wood sorrel), and in many species the leaflets fold down at night. Several species are cultivated. Some can be eaten but others are troublesome weeds (e.g. O. pes-caprae, Bermuda buttercup, which is a weed of the bulb fields of the Scilly Isles, Great Britain). There are about 500 species, found throughout the temperate and tropical regions of the world, but centred on S. Africa, and Central and S. America.