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Key lime

Key lime is a small citrus tree and fruit, usually identified as *Citrus × aurantiifolia*.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

The key lime is a small citrus tree and fruit, usually identified as *Citrus × aurantiifolia*. It is valued for its aromatic, highly acidic fruit and is closely associated with Key lime pie and tropical cooking. The plant is grown in warm climates and is also known as Mexican lime or West Indian lime.

Taxonomy and names

Key lime is commonly treated as *Citrus × aurantiifolia* and is also called Mexican lime or West Indian lime. Sources describe it as a citrus hybrid or cultivated form within the citrus family.

Description

The plant is a small evergreen citrus tree or large shrub with thorny branches, glossy leaves, and fragrant flowers. Its fruit is round, thin-skinned, and highly aromatic, with a tart and bitter taste.

Distribution and cultivation

Key lime originated in tropical Southeast Asia and was historically cultivated in the Florida Keys, which helped popularize its English common name. It is grown mainly in tropical and subtropical regions and is sensitive to frost.

Culinary use

The fruit is best known as the signature flavouring of Key lime pie. Its juice is also used in drinks, marinades, desserts, and other dishes where a strong lime flavour is desired.

Key facts

  • The key lime is a citrus plant grown for its fruit and is usually classified as *Citrus × aurantiifolia*.
  • It is smaller, seedier, thinner-rinded, and more acidic than the Persian lime.
  • The plant is native to tropical Southeast Asia and was later cultivated in the Florida Keys.
  • Key limes are commonly harvested green, although ripe fruit can turn yellow.
  • The tree is thorny and typically grows as a small, bushy evergreen.
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Canadian context

Key limes are sold in Canadian grocery stores and used in baking, cocktails, and restaurant cuisine, especially for Key lime pie and citrus desserts. In most of Canada, the plant itself must be grown indoors or in controlled conditions because it is frost tender.

Frequently asked questions

What is a key lime?
A key lime is a small citrus fruit and the tree that produces it, usually identified as *Citrus × aurantiifolia*.
Why is it called a key lime?
The name comes from its association with the Florida Keys, where it was cultivated and became widely known.
How is it different from a Persian lime?
Key limes are generally smaller, seedier, more aromatic, thinner-rinded, and more acidic than Persian limes.
Where did key limes originate?
They are native to tropical Southeast Asia and were later introduced to the Americas.
What is key lime used for?
It is most famous as the flavouring in Key lime pie, but it is also used in drinks, sauces, marinades, and desserts.
What kind of plant is a key lime tree?
It is a thorny evergreen citrus tree or large shrub that usually grows in warm climates.

References

  1. Wikipedia — https://en.wikipedia.org/wiki/Key_lime
    Supports: General description, comparison with Persian lime, and association with Florida Keys and Key lime pie.
  2. NC State Extension Plant Toolbox — https://plants.ces.ncsu.edu/plants/citrus-x-aurantiifolia/
    Supports: Common names, cultivation history in Florida Keys, and leaf description.
  3. UA Campus Arboretum — https://apps.cals.arizona.edu/arboretum/taxon.aspx?id=683
    Supports: Plant form as a small vigorous tree or large shrub.
  4. University of Florida IFAS — https://gardeningsolutions.ifas.ufl.edu/mastergardener/resources/plantid/fruits-and-nuts/lime-key/
    Supports: Tree habit, thorns, fruit description, flowering period, and comparison with Tahiti lime.
  5. USDA Forest Service / CiteSeerX copy — https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=538aecb397cdf226ed4455a6f3dc4d5f1141c652
    Supports: Common names and native range in eastern Malaysia.
  6. ECHOcommunity — https://www.echocommunity.org/es/resources/26f98477-18aa-4c0f-8329-1386cc0443f5
    Supports: Tree size, fruit characteristics, climate and frost sensitivity, and broader tropical cultivation.