The Key lime is a citrus hybrid with a spherical fruit, 2.5–5 cm in diameter. The Key lime is usually picked while it is still green, but it becomes yellow when ripe. It is smaller, seedier, has higher acidity, stronger aroma, and thinner rind.
Mexican key lime (Citrus aurantifolia), also known as key lime, bartender’s lime and West Indian lime, is a moderately sized evergreen fruit tree. It grows vigorously once you plant it in the ground, reaching heights of 6 1/2 to 13 feet tall. Mexican key lime trees have fragrant flowers with deep green leaves and the yellow-green limes that are about the size of a golf ball. Mexican key limes are the preferred fruit used by bartenders and pie bakers around the world. Growing key limes is not difficult when you meet their basic requirements.