Oxalideæ

Oxalideæ, or OXALIDACEÆ, a natural order of exogenous plants, allied to Geraniaceæ; including herbaceous plants, shrubs, and trees; with generally compound alternate leaves; calyx of five equal persistent sepals; corolla of five equal unguiculate petals, spirally twisted in bud; ten stamens; the ovary five-celled, with five styles; the fruit a capsule of five cells opening by five valves, or more rarely a berry with five one- or many-seeded cells. Temperate North America and the Cape of Good Hope may be said to be the headquarters of the order. The herbaceous parts of almost all the species are distinguished by a strong acidity, which is owing to the presence of oxalate of potash; some, however, are bitter and slightly stimulating. The fruit of some is pleasantly acid and cooling—as Carambola—and reputed to be antiscorbutic and antiseptic. The tubers of several of the typical genus (Oxalis) are eatable, and contain a considerable quantity of starchy matter. The leaves of all the species are more or less sensitive. The Wood-sorrel (O. acetosella) is a native of Britain, and one of the most elegant of the wild flowers, carpeting woods and shady places with its bright trifoliate leaves and white or rose-tinted flowers. Its leaves, resembling as they do those of the clover, have led to the surmise that it may be the true Shamrock (q.v.). The plant, which is antiscorbutic and refrigerant, is widely distributed throughout Europe, Russian and central Asia, and northern America. It is much used in salads on the Continent; and in Lapland, where it is very abundant, it is the favourite herb of the inhabitants. The expressed juice of the plant abounds in binoxalate of potash. Twenty pounds of fresh leaves yield about six pounds of juice, from which is obtained about two ounces of the pure salt.—Salt of Sorrel and Essential Salt of Lemons (see OXALIC ACID). The preparation is carried on mainly in Switzerland and Germany; not, however, exclusively from this species of Oxalis, but from several other species of the same genus and of the true sorrels (Rumex), which contain the same salt. The numerous species of Oxalis strongly resemble each other in their general appearance and properties. Several of them, such as O. crenata and O. tuberosa, natives of Peru and Bolivia, and O. Deppel, a Mexican species, are cultivated in those countries for the sake of their tuberous roots, which are eatable. These species have all been recommended for culture in Britain as substitutes for the potato, but their produce is too meagre to deserve attention; besides, the plants are constitutionally adapted only to the most favourable parts of England. Averrhoa bilimbi, or Cucumber-tree, indigenous to the East Indies, and now cultivated in some parts of South America, produces a green fleshy fruit of the shape and size of a small cucumber, which is esteemed for its grateful acid juice when ripe. The unripe fruit is also pickled.