Citrus hystrix DC.
(Rutaceae – the lemon family)
common name: Kaffir Lime, Thai Lime
Citrus is the Latin word for the citrus tree; 'υστριξ (hystrix), is the Greek word for the porcupine – prickly. The Kaffir of the common name suggests a South African connection, but I have not been able to trace this.
This is a small evergreen tree that can grow to at least 1.5 m tall, with a usually crooked trunk, a bushy habit and many short rigid thorns. Because the leaves are constantly being picked for cooking, the trees usually remain small in size. The leaves with their expanded petiole appear to be a single ‘pinched’ leaf, dark green on top, lighter on the bottom, and they are very fragrant when crushed. The tree bears small green to yellow fruits, 5–7 cm in diameter, that have a thick and very rough and wrinkled peel. The fruits have many seeds and very little juice, but the finely-grated rind and the aromatic leaves are widely used as flavouring in south-east Asian cooking. Heat-loving and frost-sensitive, the Kaffir lime thrives in tropical and sub-tropical regions. It is a native of Laos, Indonesia, Malaysia and Thailand, now grown worldwide as a back-yard shrub.
The rind of the fruit is commonly used in Laotian and Thai curry paste, adding an aromatic, astringent flavour. The leaves are used in the same cuisines for dishes such as tom yum, in Cambodian cuisine for the base paste Krueng, in Balinese and Javanese for foods such as sayur asam. The leaves can be used fresh or dried, and can be stored frozen.
The juice and rinds are used in traditional Indonesian medicine: for this reason the fruit is referred to in Indonesia as jeruk obat (‘medicine citrus’). The oil from the rind has strong insecticidal properties. The juice is generally regarded as too acidic for use in food preparation, but it finds use in Thailand as a cleanser for clothing and hair.
The zest of the fruit is used in Creole cuisine, and to impart flavour to ‘arranged’ rums in Réunion and Madagascar. Rum is ‘arranged’, following the Creole expression, by the maceration of various plants and spices or by mixing it with fruit juices. A rum can be ‘arranged’ with nearly everything : pineapple, vanilla, lychees, herbs, tangore zest, combava leaves, cinnamon, aniseed, curcuma, ginger, lemongrass, lime, cherries, mangoes, physalis, kumquat, faham, etc.
Kaffir limes make good container plants, and do well on patios and decks. Although it is possible to grow the tree from seed, grafted trees tend to bloom and bear fruit earlier than seedlings.
Photographs © Donald Simpson, taken in Picnic Bay 2011