There are two basic types of lemons and limes—acidic and sweet—but only acidic types are grown commercially. The sweet types are grown mostly by home gardeners as ornamental fruit.
Although there are some specialty lemons and limes that are identified in the marketplace, such as Key limes or Meyer lemons, the rest of the lemons and limes sold do not specify variety. There are, however, some varietal differences in size, shape, and thickness of peel, though not in flavor.
Key limes (Mexican limes): These are smaller, rounder, and yellower than most limes, with a higher acid content. They are best known as an ingredient in Key lime pie. Though Key limes were once a commercial crop in Florida, these days the majority of these limes are grown outside the United States, and used mostly in juice or juice concentrate.
Lemons: Most common everyday lemons are either Eurekas or Lisbons, though rarely does a market label their lemons as anything but “lemons.” A short neck at the stem end distinguishes Eureka lemons, whereas Lisbons have no distinct neck but the blossom end tapers to a pointed nipple. Eurekas may have a few seeds and a somewhat pitted skin, while Lisbons are commonly seedless with smoother skin. Both types have medium-thick skins and are abundantly juicy. Florida-grown lemons are likely to be Lisbon-type fruits called Bearss.
Limequats: A cross between limes and kumquats, limequats are small, round, and yellowish with an acidic lime flavor.
Makrut limes: These round, bumpy-skinned limes have very little juice, and what juice they have is bitter. They are used in Southeast Asian cooking for their zest and especially their leaves, which have fragrant oils. Makrut limes are also known as kaffir limes, but this term is increasingly controversial.
Meyer lemons: The Meyer lemon, named for Frank N. Meyer, who first imported the fruit from China in 1908, is a cross between a lemon and either an orange or a mandarin. Its orange-yellow flesh is sweeter than a lemon’s, and it has a thin, smooth skin. They can sometimes be found in specialty food stores, and are more widely available in California, where they’re the most popular variety for home growers. In the 1960s, they carried a virus that had the potential to damage other citrus crops, so their sale was restricted. A new virus-free strain has been developed, making them somewhat easier to find at farmers’ markets and produce stores.
Rangpur limes: Tart, acidic, and very juicy, these fruits resemble oranges or tangerines. They are most likely a cross between a lemon and a mandarin orange, but because they have a lime-like aroma, they have been dubbed limes.
Tahiti limes: Most of the limes in the supermarket are a Tahitian strain thought to have originated on that island. Tahiti limes come in two similar varieties: Persian limes, which are oval, egg-sized fruits cultivated in Florida, and a Bearss variety. The Bearss is a smaller, seedless California-grown lime. Both are greenish-yellow when fully mature, but are sold at their earlier, deep-green stage for better flavor.