Botanical description

Oxalis tuberosa (Oxalidaceae) is an herbaceous perennial plant that overwinters as underground stem tubers


Toxic parts

Whole plant, Leaves, Tubers

Oxalic acid, Oxalate low toxicity

The leaves contain oxalic acid, which gives them their sharp flavour. Perfectly all right in small quantities, the leaves should not be eaten in large amounts since oxalic acid can bind up the body's supply of calcium leading to nutritional deficiency. The quantity of oxalic acid will be reduced if the leaves are cooked. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet since it can aggravate their condition[12].

Varieties of this plant are grouped into those which have sweet tubers and sour tubers. The tubers of the sweet varieties contain less oxalic acid[4].
The given value was not understood.

Edible uses


Dried, Frozen as a Flour



Material uses

There are no material uses listed for Oxalis tuberosa.

Medicinal uses(Warning!)

There are no medicinal uses listed for Oxalis tuberosa.


Ecosystem niche/layer

Herbaceous, Soil surface or Rhizosphere

Ecological Functions

Nothing listed.


Nothing listed.


Nothing listed.


Oca is usually propagated vegetatively by planting whole tubers. Propagation by seed is possible but is rarely used in practice. Sexual propagation is complicated by several factors. First, like many other species in the genus Oxalis, oca flowers exhibit tristylous heterostyly and are consequently subject to auto-incompatibility. Furthermore, on the rare occasion that oca plants do produce fruit, their loculicidal capsules dehisce spontaneously, making it difficult to harvest seed. Oca flowers are pollinated by insects (e.g., genera Apis, Megachile, and Bombus). Data regarding the frequency of volunteer hybrids and farmers? subsequent incorporation of them has not yet been published[4].


Best sown as soon as it is ripe in a cold frame. Prick out the seedlings into individual pots when they are large enough to handle and plant them out in late spring or early summer.

Rooted cuttings

Basal cuttings in spring[8]. Harvest the shoots with plenty of underground stem when they are about 8 - 10cm above the ground. Pot them up into individual pots and keep them in light shade in a cold frame or greenhouse until they are rooting well. Plant them out in the summer.


Put the tuber horizontal, 10cm deep, in easy soil. Spacing 50cm by 75cm[9].


Prefers a light rich soil in a warm sunny position[13][6][8]. Tolerates a pH range from 5.3 to 7.8[8]. Plants succeed in areas with an average rainfall ranging from 570 - 2150mm per year[8]. Oka is widely cultivated in the Andes for its edible tubers, there are many named varieties[10][7]. This species has an excellent potential as a major root crop in temperate zones, it has the potential to yield as highly as potatoes but does not have the susceptibility to pests and diseases that are a bugbane for potato growers[K]. Plants are slightly more hardy than the potato, tolerating light frosts but the top-growth being severely damaged or killed by temperatures much below freezing. The main drawback is that development of the tubers is initiated by the number of hours of daylight in a day. In Britain this means that tubers do not begin to form until after the 21st of September and, if there are early frosts in the autumn, yields will be low[6]. There are possibly some forms in southern Chile that are not sensitive to daylength, these will be more suitable to higher latitudes such as Britain[8]. The varieties that are usually cultivated in New Zealand are daylength neutral. It is said that the varieties with white tubers are bitter because they contain calcium oxylate crystals whilst those with tubers that are of other colours are sweet[7]. Yields tend to average about 7 - 10 tonnes per hectare but experimentally yields of 40 tonnes per hectare have been achieved[8]. Earthing up the growing stems as they start to form tubers can increase yields significantly[8].




Tubers begin growing when day lengths begin to shorten. Harvest after the frosts have killed off top growth. The tubers are reported to continue making significant growth after the above ground parts have been killed off, so take care not to harvest too early[14]. They form in a clump close to the centre of the plants. Take care not to damage tubers as you dig them.

Yields of at least 500gr. per plant should be obtained[9], although yields vary with the cultural method. Annals from Andean countries report about 7-10 tons per hectare for Oxalis tuberosa production. But with adequate inputs and virus free propagation material, oca production can range from 35 to 55 tons per hectare[4].


Tubers of the sour cultivars are traditionally processed to form a usable storage product, called khaya in Quechua. To prepare khaya, tubers are first soaked in water for approximately one month. They are then left outside during hot, sunny days and cold, freezing nights until they become completely dehydrated.[4]. If it is washed after freezing, a whiter product called okhaya is obtained which is considered to be of superior quality.


The tubers can be stored in a cool, dry environment, much the same as for Solanum tuberosum (Potato). They can also be processed into a product named khaya, see processing notes for further information.

Problems, pests & diseases

Associations & Interactions

There are no interactions listed for Oxalis tuberosa. Do you know of an interaction that should be listed here? edit this page to add it.

Polycultures & Guilds

There are no polycultures listed which include Oxalis tuberosa.




None listed.


None listed.

Full Data

This table shows all the data stored for this plant.

Binomial name
Oxalis tuberosa
Imported References
Medicinal uses
Material uses & Functions
Edible uses
None listed.
Material uses
None listed.
Medicinal uses
None listed.
Functions & Nature
Provides forage for
Provides shelter for
Hardiness Zone
Heat Zone
full sun
no shade
Soil PH
Soil Texture
Soil Water Retention
Environmental Tolerances
    Native Climate Zones
    None listed.
    Adapted Climate Zones
    None listed.
    Native Geographical Range
    Native Environment
    Ecosystem Niche
    Root Zone Tendancy
    None listed.
    Deciduous or Evergreen
    Herbaceous or Woody
    Life Cycle
    Growth Rate
    Mature Size
    Flower Colour
    Flower Type

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    1. ? 1.01.1 Hedrick. U. P. Sturtevant's Edible Plants of the World. Dover Publications ISBN 0-486-20459-6 (32202/01/01)
    2. ? Haywood. V. H. Flowering Plants of the World. Oxford University Press ISBN 0-19-217674-9 ()
    3. ? Facciola. S. Cornucopia - A Source Book of Edible Plants. Kampong Publications ISBN 0-9628087-0-9 (32202/01/01)
    4. ? [Oca] Wikipedia (2013/05/21)
    5. ? Harrison. S. Wallis. M. Masefield. G. The Oxford Book of Food Plants. Oxford University Press (32202/01/01)
    6. ? Thompson. B. The Gardener's Assistant. Blackie and Son. (32202/01/01)
    7. ? Towle. M. A. The Ethno-Botany of Pre-Columbian Peru. ()
    8. ? Popenoe. H. et al Lost Crops of the Incas National Academy Press ISBN 0-309-04264-X (32202/01/01)
    9. ? Cite error: Invalid <ref> tag; no text was provided for refs named HowToGPV
    10. ? Organ. J. Rare Vegetables for Garden and Table. Faber (32202/01/01)
    11. ? J.E. Hernándo Bermejo and J. León [Neglected Crops: 1492 from a Different Perspective] Purdue University (2013/05/21)
    12. ? Bown. D. Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. ISBN 0-7513-020-31 (32202/01/01)
    13. ? F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press (32202/01/01)
    14. ? [Oca Instructions] The Real Seed Company (2012/12/21)
    15. ? Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press ISBN 0-333-47494-5 (32202/01/01)

    "image:Ocachezmoi.jpg|248px" cannot be used as a page name in this wiki.

    Facts about "Oxalis tuberosa"RDF feed
    Article is incompleteNo +
    Article requires citationsNo +
    Article requires cleanupNo +
    Belongs to familyOxalidaceae +
    Belongs to genusOxalis +
    Can be grown from cutting typeRoot +
    Has bulb typeNon-scaly +
    Has common nameOca +
    Has cropTubers +
    Has drought toleranceIntolerant +
    Has edible partTubers +, Flowers + and Leaves +
    Has edible useFresh + and Cooked +
    Has fertility typeSelf fertile + and Insects +
    Has flowers of typeHermaphrodite +
    Has growth rateModerate +
    Has hardiness zone7 +
    Has imageOca.jpg +
    Has lifecycle typePerennial +
    Has mature height0.45 +
    Has mature width0.3 +
    Has primary imageOca.jpg +
    Has search nameoxalis tuberosa + and x +
    Has seed requiring scarificationNo +
    Has seed requiring stratificationNo +
    Has shade toleranceNo shade +
    Has soil ph preferenceAcid +, Neutral + and Alkaline +
    Has soil teloamyture preferenceLoamy +
    Has soil tesandyture preferenceSandy +
    Has soil water retention preferenceWell drained +
    Has sun preferenceFull sun +
    Has taxonomy nameOxalis tuberosa +
    Has water requirementsmoderate +
    Inhabits ecosystem nicheHerbaceous +, Soil surface + and Rhizosphere +
    Is grown fromSeeds +, Cutting +, Bulb + and Tuber +
    Is herbaceous or woodyHerbaceous +
    Is taxonomy typeSpecies +
    Native to environmentAndes +
    Native to geographical rangeSouth America +
    Show on main page searchYes +
    Tolerates air pollutionNo +
    Tolerates maritime exposureNo +
    Tolerates nutritionally poor soilNo +
    Tolerates windNo +
    Uses mature size measurement unitMetres +