Ugli Fruits are rough skinned fruits. Ugli fruits are a cross between a grapefruit and tangerine. Ugli fruits come from South East Asia. The flesh of an ugli is sweeter than the bitter-flesh of grapefruits, so is often substituted for it. Ugli fruits can be made into preserves or even baked.
Dowell, P., Bailey, A. (1980) The Book of Ingredients, Dorling Kindersley. ISBN 0718119150.