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Key lime

life science Maturity 5-7 Next article →

The Key lime, scientifically known as *Citrus × aurantiifolia*, is a small and highly aromatic citrus fruit. It is often called the West Indian, Mexican, or Egyptian lime. While many people treat it as a single species, it actually began as a natural hybrid. It formed from the cross between *Citrus micrantha*, a wild papeda, and *Citrus medica*, known as the citron. This fruit is prized globally for its intense, acidic flavor and its distinct fragrance.

A tree full of key limes in West Bengal, India
A tree full of key limes in West Bengal, India

Growing a Key lime tree involves understanding its specific biological structure. The plant is a shrubby tree that often grows with many thorns. Its trunk rarely grows straight and frequently produces branches low on the stem. The leaves are ovate, meaning they are egg-shaped, and they closely resemble the leaves of an orange tree. The flowers are small, measuring about 1 centimeter in diameter. They appear yellowish-white with a light purple tinge along the margins.

keylime-flower
keylime-flower

From the moment a flower blooms, a specific biological process leads to the fruit. It takes approximately nine months for a blossom to develop into a full fruit. The fruit is spherical and typically measures between 3 and 6 centimeters in diameter. While the fruit is often picked while still green, it turns yellow as it reaches full ripeness. The skin is very thin and contains many glands. Inside, the pulp-vesicles are yellow-green, very juicy, and highly acidic.

KeyLime 2010 07 25 0001
KeyLime 2010 07 25 0001

The history of the Key lime is a journey across many continents. It is native to Southeast Asia. From there, it moved through the Middle East to North Africa. It eventually reached Sicily and Andalucia in Europe. Spanish explorers then carried the plant to the West Indies. In the United States, a man named Henry Perrine is credited with introducing the lime to Florida.

In Florida, the fruit became a beloved regional crop after the Great Freeze of 1894–95 destroyed lemon groves.

Farmers use different methods to grow and harvest these trees. If a farmer plants a seed, the tree may take 4 to 8 years to produce fruit. However, if they use vegetative propagation, such as cuttings or air layering, the tree can bear fruit in just one year. To ensure a strong plant, farmers sometimes graft clones onto sturdy rootstocks like wild grapefruit. This helps protect the plant from diseases like gummosis.

Dayap or Philippine keylime
Dayap or Philippine keylime

When harvesting, timing is vital. Farmers avoid picking fruit too early in the morning because the high turgor, or internal water pressure, can cause the peel oils to release and spoil the fruit.

Maintaining the fruit after it is picked is a major challenge for the industry. Key limes continue to ripen for a long time after they are harvested. To prevent spoilage, they are often stored at a relative humidity of 75–85%. Some producers use special tools like fruit wax, fungicides, or silver nitrate to extend their shelf life. In some regions, farmers use a simple coating of coconut oil to keep the limes fresh. In the Middle East, a unique process is used to create black lime. This is done by boiling the fruit in brine and then drying it to create a condiment.

Starr 080610-8303 Citrus aurantiifolia
Starr 080610-8303 Citrus aurantiifolia

The Key lime is a vital part of a much larger citrus family tree. Because it can form diploid gametes, it has the potential to create many new hybrids. For example, the Persian lime, which is the most widely produced lime in the world, is a triploid progeny of a Key lime and a lemon cross. Other varieties, like the Kirk lime, resulted from hybridization with a mandarin-pomelo cross. Even the Giant Key lime exists due to a spontaneous genomic duplication. This genetic diversity helps reduce the risk of diseases affecting the entire citrus industry.

Starr 080610-8303 Citrus aurantiifolia
Starr 080610-8303 Citrus aurantiifolia
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🖼️ Images & Media (6)
File:A tree full of key limes in West Bengal, India.jpg
A tree full of key limes in West Bengal, India.jpg
File:Map of inferred original wild ranges of the main Citrus cultivars, and selected relevant wild taxa (Fuller et al., 2017).png
Map of inferred original wild ranges of...
File:Dayap or Philippine keylime.jpg
Dayap or Philippine keylime.jpg
File:keylime-flower.jpg
keylime-flower.jpg
File:KeyLime 2010 07 25 0001.jpg
KeyLime 2010 07 25 0001.jpg
File:Starr 080610-8303 Citrus aurantiifolia.jpg
Starr 080610-8303 Citrus aurantiifolia.jpg
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