The kumquat is a small tree of Chinese origin, from the south of that enormous country. Its oval shape, the size of a gordal olive, is very characteristic, and its bright orange color is most striking.
The flavedo of this fruit—its external skin or exocarp—has a sweet flavor, while the pulp is acidic, so it contains a very peculiar balance for the taste buds. It is considered a cultivar within that species: Citrus japonica 'Nagami'