Oxalis

Oxalis ( , ) is a large genus of flowering plants in the wood-sorrel family, Oxalidaceae, comprising over 550 species. The genus occurs throughout most of the world, except for the polar areas; species diversity is particularly rich in tropical Brazil, Mexico, and South Africa. Many of the species are known as wood-sorrels (also as wood sorrels or woodsorrels) as they have an acidic taste reminiscent of the sorrel proper (Rumex acetosa), which is not closely related. Some species are called yellow sorrels or pink sorrels after the colour of their flowers instead. Other species are colloquially known as false shamrocks, and some called sourgrasses. For the genus as a whole, the term oxalises is also used. Many plants in this genus contain oxalic acid; the acid being named after the genus Oxalis.

Description

of Oxalis The 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, superficially similar to those of some clovers. Some species exhibit rapid changes in leaf angle in response to temporarily high light intensity to decrease photoinhibition. The flowers have five petals, which are usually fused at the base, and ten stamens. The petal colour 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.

Uses

As food

Several species of Oxalis are edible wild plants that have been consumed by humans around the world for millennia. In Dr. James Duke's Handbook of Edible Weeds, he notes that the Native American Kiowa people chewed wood sorrel to alleviate thirst on long trips, the Potawatomi cooked it with sugar to make a dessert, the Algonquin considered it an aphrodisiac, the Cherokee ate wood sorrel to alleviate mouth sores and a sore throat, and the Iroquois ate wood sorrel to help with cramps, fever and nausea. The fleshy, juicy edible tubers of the oca (O. tuberosa) have long been cultivated for food in Colombia and elsewhere in the northern Andes Mountains of South America. It is grown and sold in New Zealand as "New Zealand yam" (although not a true yam), and varieties are now available in yellow, orange, apricot, and pink, as well as the traditional red-orange. The leaves of scurvy-grass sorrel (O. enneaphylla) were eaten by sailors travelling around Patagonia as a source of vitamin C to avoid scurvy. In India, creeping wood sorrel (O. corniculata) is eaten only seasonally, starting in December–January. The Bodos of north east India sometimes prepare a sour fish curry with its leaves. The leaves of common wood-sorrel (O. acetosella) may be used to make a lemony-tasting tea when dried.

Other uses

(candycane sorrel) grown in New Zealand In the past, it was a practice to extract crystals of calcium oxalate for use in treating diseases and as a salt called sal acetosella or "sorrel salt" (also known as "salt of lemon"). Growing oca tuber root caps are covered in a fluorescent slush rich in harmaline and harmine which apparently suppresses pests.

As ornamental plants

Several species are grown as pot plants or as ornamental plants in gardens, for example, O. versicolor. Oxalis flowers range in colour from whites to yellow, peaches, pink, or multi-coloured flowers. Some varieties have double flowers, for example the double form of O. compressus. Some varieties are grown for their foliage, such as the dark purple-leaved O. triangularis. Species with four regular leaflets, in particular O. tetraphylla (four-leaved pink-sorrel), are sometimes misleadingly sold as "four-leaf clover", taking advantage of the mystical status of four-leaf clover.

Selected species

Oxalis acetosella – common wood-sorrel Oxalis adenophylla – Chilean oxalis, silver shamrock Oxalis albicans – hairy woodsorrel, white oxalis, radishroot woodsorrel, radishroot yellow-sorrel, California yellow-sorrel Oxalis alpina – alpine sorrel Oxalis ambigua Oxalis articulata Savign. – pink-sorrel Oxalis ausensis Oxalis barrelieri – lavender sorrel Oxalis bowiei – Bowie's wood-sorrel, Cape shamrock Oxalis brasiliensis – Brazilian woodsorrel Oxalis caerulea – blue woodsorrel Oxalis caprina Oxalis corniculata – creeping wood sorrel, procumbent yellow-sorrel, sleeping beauty, chichoda bhaji (India) Oxalis debilis Kunth Oxalis decaphylla – ten-leaved pink-sorrel, tenleaf wood sorrel Oxalis dehradunensis Oxalis depressa Oxalis dichondrifolia – peonyleaf wood sorrel Oxalis dillenii Jacquin – southern yellow woodsorrel, Dillen's woodsorrel, Sussex yellow-sorrel Oxalis drummondii – Drummond's woodsorrel, chevron oxalis Oxalis ecuadorensis Oxalis enneaphylla – scurvy-grass sorrel Oxalis exilis – least yellow-sorrel Oxalis frutescens – shrubby wood-sorrel Oxalis gigantea Oxalis glabra – finger-leaf Oxalis grandis – great yellow-sorrel, large yellow woodsorrel Oxalis griffithii Edgew. & Hook.f. Oxalis hedysaroides – fire fern Oxalis hirta – hairy sorrel Oxalis illinoensis – Illinois wood-sorrel Oxalis inaequalis Oxalis incarnata L. – pale pink-sorrel Oxalis lasiandra – Mexican shamrock Oxalis latifolia Kunth – garden pink-sorrel Oxalis luederitzii Oxalis luteola Jacq. Oxalis magellanica G.Forst. Oxalis magnifica Kunth – snowdrop wood-sorrel Oxalis massoniana Oxalis megalorrhiza – fleshy yellow-sorrel Oxalis melanosticta Oxalis montana – mountain woodsorrel, white woodsorrel Oxalis nelsonii – Nelson's sorrel Oxalis norlindiana Oxalis obliquifolia Oxalis oregana – redwood sorrel, Oregon sorrel Oxalis ortgiesii Regel – fishtail oxalis Oxalis pennelliana Oxalis pes-caprae – Bermuda-buttercup, African wood-sorrel, Bermuda sorrel, buttercup oxalis, Cape sorrel, English weed, soursob, "goat's-foot", "sourgrass", soursop (not to be confused with the fruit of that name) Oxalis priceae – tufted yellow-sorrel Oxalis pulchella Oxalis purpurea L. – purple wood-sorrel Oxalis rosea Feuillée ex Jacq. – annual pink-sorrel Oxalis rubra A.St.-Hil. – red wood-sorrel Oxalis rufescens Oxalis rugeliana – coamo Oxalis rusciformis Oxalis schaeferi Oxalis spiralis – spiral sorrel, volcanic sorrel, velvet oxalis Oxalis stricta – common yellow woodsorrel, common yellow oxalis, upright yellow-sorrel, lemon clover, "pickle plant", "sourgrass, "yellow woodsorrel" Oxalis suksdorfii – western yellow woodsorrel, western yellow oxalis Oxalis tenuifolia – thinleaf sorrel Oxalis tetraphylla – four-leaved pink-sorrel, four-leaf sorrel, Iron Cross oxalis, "lucky clover" Oxalis triangularis – threeleaf purple shamrock Oxalis trilliifolia – great oxalis, threeleaf woodsorrel Oxalis tuberosa – oca, oka, New Zealand yam Oxalis valdiviensis – Chilean yellow-sorrel Oxalis virginea – virgin wood-sorrel Oxalis versicolor – candycane sorrel Oxalis violacea – violet wood-sorrel Oxalis vulcanicola – volcanic sorrel or velvet oxalis

Names in other languages