O as in Oxalis

Family: Oxalidaceae

Genus: Oxalis

Species: Oxalis tuberosa

Common names: oca, uqa, New Zealand yam Swedish name: oca

The genus Oxalis got its name from the plants content of oxalic acid giving the leaves and flowers a sour taste. Several species are grown as container plants (indoors and outdoors) or as ornamental plants in gardens. Four common species are O. versicolor, O. compressa (double flowers), O. triangularis (dark purple foliage) and O. articulata. The flowers of the Oxalis genus range in color and shades from white to yellow, peach, pink, or multi-coloured flowers.

The fleshy, juicy tubers of Oxalis tuberosa are edible and called oca. The root vegetable is a native plant in the northern Andes and were grown by the Inca people. It is still grown by farmers in South America. Oca is an important vegetable locally due to its use in crop rotations and its high nutritional content. The tuber is a source of carbohydrate and energy. And has a valuable content of vitamin C, beta carotene, potassium and vitamin B6. It also contains small amounts of fibre. Oxalis tuberosa has a slow growth and gives less yield than potatoes so it is not common on other continents. Except for New Zealand where it was introduced in the 1800´s and became very popular. There oca often is called New Zealand yam. The tubers can be processed and prepared in various ways. The leaves and young shoots can be eaten as a green vegetable.

Oxalis tuberosa. Photo: mpaola_andreoni ©

Description: Oxalis tuberosa is a perennial herbaceous plant that overwinter as underground stem tubers. Several varieties are now available in yellow, orange, apricot, pink, as well as the traditional red-orange tubers.

How to grow: Oxalis tuberosa can be kind of tricky to grow because of its dependents of day length to grow properly. If it is to be grown as an ornamental plant other Oxalis species are preferable. Oca needs a long growing season, forming tubers when the day length shortens in autumn. In areas with harsh winter climates, early frosts may cut back the foliage before the tubers have a chance to form. In tropical areas where the days are unchanging in length, oca will not set a crop successfully. But it is quite modest in other requirements and generally grows even in marginal soil quality. Oxalis tuberosa is propagated vegetatively by planting whole tubers.

Oca or New Zealand yam. Photo: Lamerie ©

Oca or New Zealand Yam Recipes

Warm Oca Salad – recipe by Carl Legge at Permaculture

Roast Yams – recipe by CheekyKiwi at Allrecipes

Oca Homity Pie – recipe by Carl Legge at Permaculture

And for those of you who would like to try growing oca visit Growing Oca a blog by Ian Pearson.

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