Oca (New Zealand yam)
Oxalis tuberosa Molina
Botanical family: Oxalidaceae
Oxalis tuberosa, the second most cultivated tuber in the Andes after the potato, with small colourful tubers (yellow, pink, red); its young tangy leaves taste of sorrel. Sources: National Research Council, “Lost Crops of the Incas” (1989); SNHF, oca fact sheet.
Sun to partial shade
Cool, loose, humus-rich and well-drained
Regular, sensitive to summer drought
Frost-tender foliage, grown as an annual
Frost-tender in your zone
Role in permaculture
A diversifying alternative to the potato: a low, spreading ground cover, easily propagated vegetatively by tubers, low-input, and possible to grow in pots (which makes winter protection easier). A key constraint to know: tuberisation only starts under SHORT DAYS (in autumn, below ~9-10 h of daylight) while the foliage is frost-tender, a race against the frosts that makes it productive mainly in mild climates. Earthing up helps, as the tubers form at the stem nodes. Sources: SNHF; PermacultureDesign.
Companions
No companion planting is documented for this plant: no recommended neighbour, no neighbour to avoid.
Seasons & availability
Tubers form late, from September until the frosts: lifting starts in early winter, in November and December, once frost has flattened the foliage, and continues through the winter; the tubers keep several months somewhere cool and frost-free.
Available: January, February, March, November, December.
Guidance for the oceanic / temperate climate; it may vary with your region, altitude, exposure and growing method.
Sources
- Plants For A Future, « Oxalis tuberosa » (pfaf.org/user/Plant.aspx?LatinName=Oxalis+tuberosa)
- La Forêt Nourricière, « Oca du Pérou, Oxalis tuberosa » (laforetnourriciere.org/produit/oca-du-perou-oxalis-tuberosa/)
Nutritional & medicinal properties
For educational purposes. Not a substitute for medical advice. Effects depend on the form, the dose and personal context.
Precautions & contraindications
The whole plant (tubers and leaves) is rich in oxalates, with a content that varies by cultivar, on the order of 90 to 220 mg/100 g for the fresh tuber (Ross et al., 1999, J. Agric. Food Chem., DOI 10.1021/jf990332r). Like sorrel or spinach, to be eaten in moderation, particularly in case of a tendency to oxalate kidney stones, gout, or kidney failure. Cooking, exposing the tubers to the sun, and pairing with a source of calcium reduce their impact. Does not replace medical advice.
Species & varieties
The best-known species and varieties in France.
Common varieties
Key takeaways
- • Prefers sun to partial shade exposure.
- • Ideal soil: cool, loose, humus-rich and well-drained.