Oca tubers are from the perennial Oxalis tuberosa plant; they are traditionally eaten boiled in soups and stews. Evidence from historic accounts indicates that oca was a major Andean staple in pre-Colombian times, second in importance to potato. Experiments have shown that oca could replace wheat flour in the preparation of bread. Although the crop is grown with very low production inputs and generally on plots of marginal soil quality, oca easily yields as much as potato. With adequate inputs, oca production can range from 35 to 55 tons per hectare, with single plants yielding up to 4 kilograms. Oca appears to be a hardier plant than ulluco as it grows at higher elevations, up to 4100 meters. However, its cultivation is severely constrained by the oca weevil, a beetle often destroying entire crops.