Kaffir lime

This is a Thai lime tree.

It is a small tree with thorns. The fruit is green and bumpy. It can turn yellow when it is ripe.

The leaves have a special shape. They look like two leaves joined together. These leaves smell very strong.

People use the leaves in many meals. They use them in many lands in Asia. The fruit juice can even be used in shampoo.

It is a very useful plant.

The kaffir lime is a small tree or thorny shrub. It comes from tropical Southeast Asia. This plant has very special leaves. They look like two leaves joined together. These leaves have a strong smell. The fruit is small and green. It has a bumpy skin. It can turn yellow when it is ripe. The fruit has a thick skin called a pericarp. The fruit tastes very sour and a bit bitter.

Many people use this plant for food. In Thailand and Cambodia, people use the leaves in many dishes. In Vietnam, the leaves add a nice smell to chicken. People also use the fruit peel in curry paste. In some places, people even eat the whole fruit as a sweet treat.

The plant's oil is very useful too. This oil is used to make perfumes. It is also used in soaps and beauty products. Some people use the juice as a shampoo. In the past, people in Sri Lanka rubbed the juice on their legs. They did this to keep leeches away. This helped give the fruit the name "Leech Lime."

The kaffir lime is a special plant from tropical Southeast Asia.

It grows as a thorny shrub or a small tree. This plant is important because many people use it for food. People also use it to make perfumes and soaps. Its leaves and fruit have a very strong, citrus smell. This scent comes from natural oils inside the plant. The plant is useful in many different ways every day.

This plant has a very unique way it works. The leaves look like two leaves joined together in an hourglass shape. This happens because the leaf has a flattened, leaf-like stalk. The fruit is small and has a very bumpy skin. It starts out green and turns yellow when it is ripe. The fruit has a thick skin called a pericarp. This skin and the juice taste very sour and a bit bitter.

People have studied this plant for a long time. Pierre Sonnerat collected specimens of it in 1771 or 1772. Later, it appeared in a book by Lamarck in 1796. In 1868, texts used the name kaffir lime in Ceylon. In that place, people used the juice to stop leech bites. Because of this, it was sometimes called leech lime. Different names are used in places like Thailand, Laos, and Vietnam.

There are many interesting facts about this citrus fruit. The leaf oil contains up to 80 percent citronellal. This is the part that gives it a strong aroma. In Vietnam, people use the leaves with chicken or steamed snails. In Cambodia, people sometimes eat the whole fruit as a sweet treat. In Mauritius and Madagascar, the zest is used in creole cooking. The fruit is also used in religious ceremonies in Cambodia.

You might recognize this plant if you like cooking. Many Southeast Asian dishes, like Thai tom yum, use these leaves. The leaves can be fresh, dried, or even frozen. The fruit peel is often used to make curry paste. You might also find its oil in your favorite shampoo or perfume. It is even used in aromatherapy to help people relax. This plant connects many different cultures through its unique smell and taste.

The kaffir lime, scientifically known as *Citrus hystrix*, is a unique citrus plant native to tropical Southeast Asia. It is highly valued for its intense fragrance and its specific uses in cooking and industry.

People use its fruit and leaves in many Southeast Asian cuisines. Additionally, the essential oils extracted from the plant are used in perfumery and cosmetics. This plant is a significant part of the botanical and culinary landscape in many tropical regions.

Physically, *Citrus hystrix* grows as a tall, thorny shrub or a small tree. The plant is easily identified by its distinctive "double" leaves. These leaves have an hourglass shape because of a feature called a winged petiole. This is a flattened, leaf-like stalk that makes the leaf look like two pieces joined together. The fruit itself is quite small and has a very bumpy, rough exterior. It starts as a green color and eventually ripens to yellow.

The fruit has a thick skin, which is botanically known as the pericarp. This skin and the juice inside are both very acidic and slightly bitter.

There are many different names for this plant depending on the region. In Indonesia and Malaysia, the names refer to its "warty" or "rough-skinned" texture. In China, it is known as the "arrow-leaf lime." In Thailand, it is called *makrut*, a name also used for the bergamot orange. The plant has a complicated history regarding its primary common name. Some suggest the name comes from the Kaffirs, an ethnic group in Sri Lanka. Others suggest the name was used by Indian Muslims to denote an exotic origin. Because the term "kaffir" is an ethnic slur in South Africa, many authors now prefer the name "makrut lime" or "Thai lime" to remain neutral.

Scientific interest in the plant dates back several centuries. Pierre Sonnerat collected specimens of the plant between 1771 and 1772. Later, the plant was documented in Lamarck's *Encyclopédie Méthodique* in 1796. In 1868, texts in Ceylon referred to the plant as the kaffir lime. In Ceylon, people would rub the juice on their legs and socks to prevent leech bites. This specific use led to the plant being called "leech lime" in some historical records.

The plant's powerful scent is caused by specific chemical compounds. The leaf oil contains up to 80 percent of a compound called (–)-(S)-citronellal. This is the main substance responsible for its characteristic aroma. Other components in the leaf oil include citronellol, which makes up about 10 percent, as well as nerol and limonene. Interestingly, the leaves contain only the (S) stereoisomer of citronellal. This is different from lemon balm, which contains the (+)-(R) version. The fruit peel contains different oils, primarily limonene and β-pinene.

Culinary uses for *Citrus hystrix* are widespread across many different cultures. In Thailand, the leaves are a key ingredient in dishes like tom yum. In Cambodia, the leaves form the base of a paste called "krueng." Vietnamese cooks use the leaves to add fragrance to chicken or to reduce the odor when steaming snails. In some Vietnamese villages, silkworm pupae are stir-fried with these leaves. In the islands of Mauritius, Réunion, and Madagascar, the zest is used in creole cooking. In Cambodia, the entire fruit can even be candied for eating.

Beyond the kitchen, the plant has many medicinal and industrial applications. The juice is used in traditional medicine and can be used in shampoo to kill head lice. In Thailand and Cambodia, the juice also serves as a cleanser for hair and clothing. In Cambodia, slices of the fruit are used in lustral water for religious ceremonies. The essential oils are also used in the pharmaceutical, cosmetic, and perfume industries. However, users should be careful because the plant contains furanocoumarins. These compounds can cause phytophotodermatitis, which is a type of skin inflammation caused by sunlight.