Quince, the fruit of a species of Pirus (P. cydonia), a member of the rose family. The species is sometimes regarded as entitled to separate, generic rank, and is then called Cydonia vulgaris. It is said to be a native of northern Persia, but is naturalized through the northern hemisphere. There are only three principal varieties in cultivation: Those in which the fruit is apple-shaped; those in which it is pear-shaped; and the so-called Portugal quince, which has very large fruit.