|Oxalis subsp. var.||Oxalis|
Oxalis (pronounced /ˈɒksəlɪs/) is by far the largest genus in the wood-sorrel family Oxalidaceae: of the approximately 900 known species in the Oxalidaceae, 800 belong here. The genus occurs throughout most of the world.
Includes species are known as wood-sorrels, yellow-sorrels, pink-sorrels, false shamrocks, and "sourgrasses".
These plants are annual or perennial. The leaves are divided into three to ten or more obovate and top notched leaflets, arranged palmately with all the leaflets of roughly equal size. The majority of species have three leaflets; in these species, the leaves are superficially similar to those of some clovers.
The flowers have five petals, which are usually fused at the base, and ten stamens. The petal color varies from white to pink, red or yellow; anthocyanins and xanthophylls may be present or absent but are generally not both present together in significant quantities, meaning that few wood-sorrels have bright orange flowers. The fruit is a small capsule containing several seeds. The roots are often tuberous and succulent, and several species also reproduce vegetatively by production of bulbils, which detach to produce new plants.
Some species – notably Bermuda-buttercup (O. pes-caprae) and creeping woodsorrel (O. corniculata) – are pernicious invasive weeds when escaping from cultivation outside their native ranges; the ability of most wood-sorrels to store reserve energy in their tubers makes them quite resistant to most weed control techniques.
|Standard Cyclopedia of Horticulture|
Oxalis (Greek, sharp, referring to the usual acidity of the foliage, which also gives the common name of sorrel). Oxalidaceae, formerly treated as a division of Geraniaceae. Mostly bulbous or tuberous herbs with clover-like leaves, usually cultivated as hanging-basket or window plants for their flowers; a few are used in salads and several South American species like O. Deppei (Gn. 8, p. 43) furnish edible roots or tubers.
Annual, or with a bulbous, tuberous or creeping, perennial rootstpck: lys. alternate, mostly digitateiy compound (3-foliolate in the native species): peduncles axillary, 1- to several-fld.; sepals and petals 5; stamens 10, monadelphous at base, 5 longer and 5 shorter; ovary 5-celled; several ovules in each cell; styles 5: caps, loculicidally dehiscent.—Over 400 species mostly of S. Afr. and the warmer parts of Amer. The fls. usually close at night and in cloudy weather, and the Lvs. "sleep" at night. Trimorphic heterogone fls. occur in many species; our native O. violacea, sometimes grown as a hardy perennial, presents long- and short-styled fls.; and our common native yellow-fld. species offer puzzling transitions between heterogone and homogone types. The small seeds are interestingly discharged from the fr. by the pressure of a fleshy outer envelope. The classical works on the genus are Jacquin's Oxalis Monographia (1794) and Zuccarini's Monographic der Amenkanischen Oxalis-Arten, and its Nachtrag (1825-31). Many of the earlier species, characterized by the relative length of stamens and styles, prove to be long-, short-, and mid-styled forms of identical species. The principal groups are sometimes segregated as distinct genera.
Generally speaking, the genus Oxalis is not highly esteemed by the florists. However, several species and varieties are used in masses for floral displays in botanical collections. The noteworthy species occasionally seen are O. Bowiei, O. lasiandra and its varieties alba, caerulescens and lilacina, O. variabilis and its varieties alba and rubra, O. Simsii, and O. rosea. When used for display during February or March, the bulbs or tubers should be cleaned and divided into convenient sizes during August or September. Excellent results may be accomplished by potting three bulbs, forming a triangle in each 4-inch spot, placing them just below the surface of the soil. The soil ingredients should consist of loam, leaf-soil and sand, in proportion to give a good porous medium. As root" action and growth increase, repot into 5- or 6-inch pots, which will carry them throughout the flowering period. Occasionally the crowns have a tendency to rise above the level of the soil; these may be lowered during repotting. When the plants are well rooted, periodical watering with organic fertilizer will help the development of good substantial flowers. During growth place the plants on the side stages near the glass in a temperature of 60° F. After the flowering period gradually reduce the water-supply and finally place in a cool cellar for the resting-period or under the greenhouse bench, laying the pots side down. Specimen clumps are an acquisition planted below the benches in the floral display house; under these conditions they will practically naturalize themselves. Plants are also conveniently grown as common house plants, either in hanging-baskets or as pot-plants for the window during the summer months. When dormant they are easily stored in the cellar. A disappointing feature is the partial closing of the flowers during dull weather.
O. japonica, Franch. & Sav. Lfts. broadly triangular, scarcely notched, and truncate. Otherwise similar to O. Acetosella. Japan. —O. violacea. Linn. Lvs. rather fleshy, glabrous: fls. in simple umbels, rose-violet. E. U.S.—Scarcely useful, except for hardy borders or rockeries.
Pests and diseases
- ↑ Sunset Western Garden Book, 1995:606–607
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963