The lemon is a human invention, only a few thousand years old, and is thought to have come from East Asia. The lemon is a cross breed of several fruits, including the bitter orange and the citron. The bitter orange is a hybrid of two other citrus fruits: the pomelo and the mandarin, while the citron, which looks a lot like the lemons that are so popular today, has skin that isn’t as smooth and yields less juice than lemons. Gradually, the lemon made its way west, eventually arriving in Italy in the first century BCE and spreading to five different continents thanks to Christopher Columbus. Scottish physician James Lind conducted one of the first clinical trials in history and discovered that lemon juice could prevent scurvy. Today, there are over two dozen commercially produced varieties of lemons.
https://www.trueorbetter.com/2018/05/how-lemon-was-invented.html