Key limes get their name from the Florida Keys, the chain of small islands stretching off the southern tip of Florida where these limes were once grown commercially. The fruit itself originated in Southeast Asia and traveled thousands of miles over centuries before becoming so closely identified with this one narrow strip of American geography that it took on the name permanently.
How an Asian Fruit Ended Up in the Florida Keys
The key lime is a natural hybrid between two wild citrus species, first cultivated as a fruit crop more than 4,000 years ago in Southeast Asia. Arab traders carried it westward across the Middle East and into North Africa, and Spanish and Portuguese explorers eventually brought it to the Caribbean and the Americas in the 1500s. The warm, tropical climate of the Florida Keys turned out to be ideal for the fruit, and by the 1800s, small lime groves dotted the islands.
For decades, these limes were simply called “limes” because they were the only variety most Floridians knew. The distinction only became necessary later, when a larger, seedless variety called the Persian lime (also known as the Tahiti lime) arrived in Florida around 1883. Suddenly there were two limes on the market, and people needed a way to tell them apart. The small, seedy, aromatic limes that had long thrived in the Keys became “Key limes,” while the bigger newcomers became the standard grocery store lime we see today.
Why the Name Stuck After the Trees Disappeared
A series of devastating hurricanes in the early 20th century wiped out most of Florida’s commercial Key lime groves. Growers who replanted largely switched to Persian limes, which were hardier, seedless, and easier to ship. Key limes essentially vanished from large-scale Florida agriculture.
But the name had already cemented itself in American food culture, largely thanks to Key lime pie. Food historians trace versions of the pie in the Florida Keys back to at least the 1890s. The recipe made practical sense for island life: sweetened condensed milk, which didn’t need refrigeration, was mixed with the tart juice of local limes and egg yolks. The acid in the juice thickened the condensed milk without any baking required. A “Tropical Lime Chiffon Pie” appeared in a 1933 Miami newspaper, and by 1935, “icebox lime pie” was already being described as a specialty of the Keys. The pie became so iconic that Florida designated Key lime pie as the official state pie in 2006.
Pastry chef Stella Parks has traced the recipe’s likely ancestor to a 1931 promotional brochure from Borden, a condensed milk company, which published a “Magic Lemon Cream Pie” recipe. Home cooks in the Keys swapped in their local limes for the lemons, creating a regional classic. Parks described it as “a stunning reminder of how deeply America’s traditions are shaped by advertising.”
How Key Limes Differ From Regular Limes
The limes you typically find at the grocery store are Persian limes, and they’re noticeably different from Key limes in almost every way. A Persian lime weighs about 3 ounces on average. A Key lime weighs roughly 1 ounce, about the size of a golf ball. Cut one open and you’ll find thinner skin, more seeds, and juice that’s yellow rather than green.
The flavor is the real distinction. Key limes are less tart and more floral than Persian limes, with a stronger, more complex aroma. Persian limes actually have higher acidity and a lower pH despite tasting more straightforward. That floral intensity is what makes Key lime juice so recognizable in pies and cocktails, and why many bakers insist that substituting regular lime juice doesn’t produce the same result.
Where Key Limes Come From Today
Almost no commercial Key lime production remains in Florida. The Key limes sold in American stores today come overwhelmingly from Mexico, which exported over 722,000 metric tons of limes to the United States in 2024. They’re also grown in parts of Central America, the Caribbean, and Brazil. You can still find Key lime trees in backyards and small gardens throughout the Florida Keys, but the commercial industry that gave the fruit its name has been gone for nearly a century.
The name “Key lime” is primarily an American term. In much of the world, the same fruit goes by “Mexican lime” or simply “lime,” since it remains the dominant lime variety in tropical regions. The Persian lime, so common in U.S. supermarkets, is actually the oddity globally. In naming the smaller fruit after a tiny archipelago rather than its vast growing range, Americans preserved a piece of Florida culinary history in the produce aisle.