A version of this story appears in the February 2017 issue of National Geographic magazine. Citrus, in many ways, stands alone. So many cultivated species have come from so few primary ancestors.

Fruit trees. Now through winter and into early spring is when Eureka lemons are ready for harvest. You will find a few Eureka ...

Toss in salads: Citrus fruits, including kumquats, are ideal for adding color and texture to salads. Take a tip from Alfred ...

In fact, citrus fruit immediately begin to deteriorate upon being detached from the tree but, if refrigerated ... is a member of the cabbage family. Red Russian is widely regarded as the mildest ...