Oxalis ( (British English)[ Sunset Western Garden Book 1995:606–607]) is a large genus of in the wood-sorrel family, Oxalidaceae, comprising over 550 species.
Many of the species are known as wood-sorrels
Description
The plants are
annual plant 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
.
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 . The petal colour varies from white to pink, red or yellow;
Ecology
Several
Oxalis species dominate the plant life in local woodland ecosystems, be it Coast Range ecoregion of the
Pacific Northwest, or the Sydney Turpentine-Ironbark Forest in southeastern Australia where least yellow sorrel (
Oxalis exilis) is common. In the United Kingdom and neighboring Europe, common wood sorrel (
O. acetosella) is the typical woodland member of this genus, forming large swaths in the typical mixed deciduous forests dominated by downy birch (
Betula pubescens) and sessile oak (
Quercus petraea), by sycamore maple (
Acer pseudoplatanus),
Bracken (
Pteridium aquilinum), pedunculate oak (
Quercus robur) and
blackberries (
Rubus fruticosus agg.), or by common ash (
Fraxinus excelsior), dog's mercury (
Mercurialis perennis) and European rowan (
Sorbus aucuparia); it is also common in woods of common juniper (
Juniperus communis ssp.
communis). 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.
A 2019 study
Tuberous woodsorrels provide food for certain small , such as the Montezuma quail ( Cyrtonyx montezumae). The foliage is eaten by some Lepidoptera, such as the Polyommatini pale grass blue ( Pseudozizeeria maha), which feeds on creeping wood sorrel and others, and Zizeeria lysimon ( Zizeeria lysimon).
Oxalis species are susceptible to the rust fungus ( Puccinia oxalidis).
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 people 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 of the Oxalis tuberosa ( 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 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 Bodo people 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
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
are covered in a
fluorescent slush rich in
harmaline and
harmine which apparently suppresses pests.
[Bais et al. (2002, 2003)]
As ornamental plants
Several species are grown as
or as
in
, 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
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Oxalis acetosella – common wood-sorrel
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Oxalis adenophylla – Chilean oxalis, silver shamrock
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Oxalis albicans – hairy woodsorrel, white oxalis, radishroot woodsorrel, radishroot yellow-sorrel, California yellow-sorrel
-
Oxalis alpina – alpine sorrel
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Oxalis ambigua
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Oxalis articulata Savign. – pink-sorrel
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Oxalis ausensis
-
Oxalis barrelieri – lavender sorrel
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Oxalis bowiei – Bowie's wood-sorrel, Cape shamrock
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Oxalis brasiliensis – Brazilian woodsorrel
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Oxalis caerulea – blue woodsorrel
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Oxalis caprina
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Oxalis corniculata – creeping wood sorrel, procumbent yellow-sorrel, sleeping beauty, chichoda bhaji (India)
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Oxalis debilis Kunth
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Oxalis decaphylla – ten-leaved pink-sorrel, tenleaf wood sorrel
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Oxalis dehradunensis
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Oxalis depressa
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Oxalis dichondrifolia – peonyleaf wood sorrel
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Oxalis dillenii Jacquin – southern yellow woodsorrel, Dillen's woodsorrel, Sussex yellow-sorrel
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Oxalis drummondii – Drummond's woodsorrel, chevron oxalis
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Oxalis ecuadorensis
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Oxalis enneaphylla – scurvy-grass sorrel
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Oxalis exilis – least yellow-sorrel
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Oxalis frutescens – shrubby wood-sorrel
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Oxalis gigantea
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Oxalis glabra – finger-leaf
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Oxalis grandis – great yellow-sorrel, large yellow woodsorrel
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Oxalis griffithii Edgew. & Hook.f.
-
Oxalis hedysaroides – fire fern
-
Oxalis hirta – hairy sorrel
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Oxalis illinoensis – Illinois wood-sorrel
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Oxalis inaequalis
-
Oxalis incarnata L. – pale pink-sorrel
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Oxalis lasiandra – Mexican shamrock
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Oxalis latifolia Kunth – garden pink-sorrel
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Oxalis luederitzii
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Oxalis luteola Jacq.
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Oxalis magellanica G.Forst.
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Oxalis magnifica Kunth – snowdrop wood-sorrel
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Oxalis massoniana
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Oxalis megalorrhiza – fleshy yellow-sorrel
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Oxalis melanosticta
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Oxalis micrantha – dwarf woodsorrel
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Oxalis montana – mountain woodsorrel, white woodsorrel
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Oxalis nelsonii – Nelson's sorrel
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Oxalis norlindiana
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Oxalis obliquifolia
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Oxalis oregana – redwood sorrel, Oregon sorrel
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Oxalis ortgiesii Regel – fishtail oxalis
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Oxalis pennelliana
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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 soursop)
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Oxalis priceae – tufted yellow-sorrel
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Oxalis pulchella
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Oxalis purpurea L. – purple wood-sorrel
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Oxalis rosea Feuillée ex Jacq. – annual pink-sorrel
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Oxalis rubra A.St.-Hil. – red wood-sorrel
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Oxalis rufescens
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Oxalis rugeliana – coamo
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Oxalis rusciformis
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Oxalis schaeferi
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Oxalis spiralis – spiral sorrel, volcanic sorrel, velvet oxalis
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Oxalis stricta – common yellow woodsorrel, common yellow oxalis, upright yellow-sorrel, lemon clover, "pickle plant", "sourgrass, "yellow woodsorrel"
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Oxalis suksdorfii – western yellow woodsorrel, western yellow oxalis
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Oxalis tenuifolia – thinleaf sorrel
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Oxalis tetraphylla – four-leaved pink-sorrel, four-leaf sorrel, Iron Cross oxalis, "lucky clover"
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Oxalis triangularis – threeleaf purple shamrock
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Oxalis trilliifolia – great oxalis, threeleaf woodsorrel
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Oxalis tuberosa – oca, oka, New Zealand yam
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Oxalis valdiviensis – Chilean yellow-sorrel
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Oxalis virginea – virgin wood-sorrel
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Oxalis versicolor – candycane sorrel
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Oxalis violacea – violet wood-sorrel
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Oxalis vulcanicola – volcanic sorrel or velvet oxalis
Further reading
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Bais, Harsh Pal; Vepachedu, Ramarao & Vivanco, Jorge M. (2003): Root specific elicitation and exudation of fluorescent β-carbolines in transformed root cultures of Oxalis tuberosa. Plant Physiology and Biochemistry 41(4): 345–353. Preprint PDF fulltext
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Łuczaj, Łukasz (2008): Archival data on wild food plants used in Poland in 1948. Journal of Ethnobiology and Ethnomedicine 4: 4. PDF fulltext
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