The Key lime is a citrus species with a globose fruit, 2.5–5 cm in diameter (1–2 in), that is yellow when ripe but usually picked green commercially. It is smaller and seedier, with a higher acidity, a stronger aroma, and a thinner rind, than that of the Persian lime (Citrus Latifolia). It is valued for its unique flavor compared to other limes, with the Key lime usually having a more tart and bitter flavor. The name comes from its association with the Florida Keys, where it is best known as the flavoring ingredient in Key lime pie. Key Lime Essential Oil has a tart, fresh scent characteristic of the fruit.