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.

Orange trees are one of the most recognized types of citrus trees featuring full ... a naval orange tree is not as cold-hardy as a mandarin orange tree. The fruit may split its skin during ...

One glass will require about three mandarin ... for an orange seed to grow into an actual tree – but it’s worth the wait! A little nurturing and patience is all it takes. Tangerine, satsuma, ...