FROM oranges and lemons to limes and grapefruit, the wealth of citrus fruits available today belies the fact that there are only three true citrus species. So says a researcher in Florida, who insists all the rest are mongrels resulting from different combinations of pomelos, citrons and mandarins.
Records of citrus cultivation stretch back to 2100 BC, but scientists have always disagreed about how many species there are in this plant genus. Some researchers argue that they all belong to a single species, while others have suggested there are as many as 147.
Several factors make classification difficult. First, it…
