All of the citrus fruits are from the family Rutaceae. This family is also known as the rue family and contains flowering plants that generally have a strong scent. The genus Citrus includes oranges, grapefruits, limes and lemons.

All of the citrus fruits are noted for their fragrance. This is due to limonoids and flavonoids (both of which have strong antioxidant and antibacterial properties). They can help prevent kidney stones, as they contain high levels of citrate. Lemons are the highest, drinking diluted lemon juice daily has been shown to decrease kidney stone formation.