OXALIS (Lat., from Gk. sorrel). A genus of the natural order Geraniacefe, accord ing to Bentham and Hooker, including herbs and shrubs with generally compound alternate digi tate or ternate, rarefy simple or pinnate leaves. There are upward of 200 known species, na tives of warm and temperate climates, par ticularly abundant in North America and at the Cape of Good Hope. The genus Oxalis has a capsular fruit. and the seeds have an elastic in tegument, which, bursting open. projects the seed to a distance. The stems and leaves gen erally contain a notable quantity of binoxalate of potash. and have, therefore, a sour taste. The common wood sorrel (Oxalis .Icetosella), very abundant in shady woods and groves in most parts of Europe, a native also of North America, is a beautiful little plant. often covering the ground with its green leaves, amid which the white or slightly roseate flowers appear. Its leaves all grow from the rootstock, a long leaf stalk bearing three ohovate leaflets, the scape a single flower. On account of their grateful acid taste, due to oxalic acid (q.v.), the leaves are used in salads and sauces. The plant is extreme ly abundant in Lapland, and is much used by the Laplanders. Oxalis eorniculata, a plant of very extensive distribution, being found in Eu rope, North America, India, Japan. and some of the African islands, has a branched stem, with decumbent branches, leaves very similar to those of the common wood sorrel. and yellow flowers. Its properties agree with those of the common wood sorrel. Many other species resemble these in general appearance and properties. The leaves of some of the species exhibit an irritability like that of the sensitive plant. generally in a slight degree. and notably only in hot sunshine, but
Oxalis sensitira or Biophytum sensitirum, an East Indian species. with pinnate leaves. pos sesses this property in a high degree. Some spe cies, as Oxalis certitta, a native of South Africa. are remarkable for producing large hulbels in the arils of the lower leaves. Several species have tuberous roots, and are cultivated on account of their tubers, as Oxalis crenata and Oxalis tube rosa. natives of Peru and Bolivia. where they are much esteemed. both receiving the name oca. The tubers when cooked become mealy like po tatoes. They have a slightly acid taste. Oxalis crenata has been cultivated in gardens for many years, but continues to he almost exclusively an object of curiosity. too tender for temperate climates and its product very inconsiderable in quantity. Its tubers are yellow. in size and shape like small potatoes. The succulent stalks of the leaves abound in a pleasant acid juice. and make excellent tarts and preserves. Oxalis tuberosa produces numerous small tubers. The Bolivians often expose them for a long time to the sun, by which they lose acidity. become sac charine, and acquire a taste and consistence like dried figs. Oxalis Deppei is a Mexican species, with a root somewhat like a small parsnip, quite free of acidity. It is much cultivated in its native country, and succeed: well in the southern parts of England. Oxalis tetraphylla and Oxalis crassicaulis, natives of :Mexico. and Oxalis en ncphylla, a native of the Falkland Islands. also have edible roots. Many species of Oxalis are much esteemed as ornaments of gardens and greenhouses.