Oranges and lemons: clues to the taxonomy of Citrus from molecular markers

Go into any grocery store and one is confronted with an array of Citrus fru it: oranges, grapefruit, mandarins (tangerines), lemons and limes. This is rich bounty for the shopper, but taxonomists are perplexed as to how to cla ssify the various kinds of Citrus that have existed since antiquity. Now, t hanks to new genetic and molecular biological techniques, the relationships between these fruit are being unraveled and show that there are probably o nly three true species.