Kumquat

The name kumquat comes from the Cantonese for golden orange, a likely description of this brilliant fruit. Introduced into the United States about 1850, the kumquat has been cultivated ever since in small quantities in Florida and California. The two varieties that have been most successful are the oblong Nagami and the round Meiwa, both about 1½ inches long, both of Japanese origin. Although similar, the Meiwa is usually sweeter and more tender.

The kumquat was considered a Citrus until 1915, when scientists found cellular differences sufficient to warrant moving it into its own genus, Fortunella (named after Robert Fortune, an English traveler who introduced the kumquat into Europe in 1846). I think a better reason to have moved its grouping might be that it is the only fruit with a rind that is deliously sweet and pulp that is puckery-sour!