Its fruit is 2.5-5 cm in diameter (1-2 in). The fruit is yellow when ripe but usually it is picked green. It is smaller, seedier, has a higher acidity, a stronger aroma, and a thinner rind than that of the more common Persian lime. It is valued for its unique flavor compared to other lime. The Key lime usually has a more tart and bitter flavor. It is perhaps most distinguished as an ingredient in the Key lime pie. 