Calamondin, Citrus mitis, is an acid citrus fruit originating in China, which was introduced to the U.S. as an "acid orange" about 1900. This plant is grown more for its looks than for its fruit edibility and performs well as a patio plant or when trimmed as a hedge. It is hardy to 20 degrees F. and is hardier to cold than any other true citrus specie---only the trifoliate orange and the kumquat are more tolerant to low temperatures. The edible fruit is small and orange, about one inch in diameter, and resembles a small tangerine.