What is "oxalis tuberosa"

Oca \O"ca\, n. [Sp.] (Bot.) A Peruvian name for certain species of Oxalis ( Oxalis crenata, and Oxalis tuberosa) which bear edible tubers.

Oxalis tuberosa (Oxalidaceae) is a perennial herbaceous plant that overwinters as underground stem tubers. These tubers are known as uqa in Quechua, Hispanicized oca, as New Zealand yam and a number of other alternative names. The plant was brought into cultivation in the central and southern Andes for its tubers, which are used as a root vegetable. The plant is not known in the wild, but populations of wild Oxalis species that bear smaller tubers are known from four areas of the central Andean region. Oca was introduced to Europe in 1830 as a competitor to the potato, and to New Zealand as early as 1860.

In New Zealand, oca has become a popular table vegetable and is simply called yam or New Zealand yam (although not a true yam). It is now available in a range of colours, including yellow, orange, pink, apricot, and the traditional red.