Citrus paradisi x Citrus reticulata:
A natural hybrid is thought to be a grapefruit x mandarin. Large knobbly fruit, the variety was discovered in Jamaica in 1914. Traditionally eaten like a grapefruit, we peal and eat them just like an orange. Its flavour and texture is uniquely rich.
The story of it's name is steeped in myths but the one that keeps popping up is:
A plantation owner in Jamaica walks into his kitchen and plonks a large fruit on the table.
His cook takes one look at it and exclaims "Man that's one UGLI fruit!"