Citrus x aurantiifolia 'Mexican'

The Lime tree or Mexican Lime, in Latin Citrus aurantiifolia, is a moderately vigorous citrus tree, with a well-branched and highly floriferous habit in spring. Its small, pleasantly scented white star-shaped flowers are followed by small, more or less spherical fruits covered with a smooth and thin skin. The pulp of this citrus fruit is very juicy, particularly acidic but highly aromatic, when the skin turns yellow. This variety, the least hardy of all citrus trees, has very specific tropical requirements: it perishes below -3°C (26.6°F) and requires warmth throughout the year to fruit well. It can be cultivated in a large container and stored in a slightly heated greenhouse in winter, or in open ground in warm regions that are spared from frost.

Citrus aurantifolia is also known as Acid Lime, Country Lime, Pebble Lime, Mexican Lime or even West Indian Lime depending on the region. It is a spiny bush from the Rutaceae family, with a rather upright and bushy habit. It is likely native to Southeast Asia, specifically Malaysia and the Philippines, but its exact origin is somewhat unclear. Recent studies suggest a hybrid origin between Citrus medica (the citron) and C. micrantha (a small wild lime from the Philippines). The 'Mexican' selection produces remarkably fragrant small fruits.

This small tree reaches a height of 3.50m (11ft). Its branches are short and bear numerous short and sharp thorns. Not very hardy, it can be planted in open ground on a narrow stretch of the Mediterranean coast, in non-calcareous soil only. Elsewhere, it should be cultivated in a pot and stored at the onset of the first frosts. Primarily grown for its fruits, the lime tree blooms abundantly in March-April, and then again, more sporadically, until autumn in a Mediterranean climate. It produces small white flowers, slightly tinged with yellow at the centre and with a sweet and delicious neroli fragrance, characteristic of Citrus. These give way to oval to round fruits, resembling yellow lemons, measuring 3 to 5cm (1 to 2in) in diameter. Their very thin and smooth skin is initially dark green, then turns green-yellow. The fruit's pulp, white-greenish and translucent, is both very juicy and very acidic, and contains a few seeds. The fruits are harvested when they start to turn yellow, at the peak of their essential oil content. The evergreen and aromatic leaves of this citrus tree are ovate, leathery, small, and intensely green in colour. 

Limes are part of the culinary traditions of several Southeast Asian countries, as well as Reunion Island and the Caribbean. Their use is almost as widespread as that of yellow lemons, in savoury or sweet dishes. The juice is used in refreshing drinks or cocktails, adding a touch of acidity and a unique aroma. The zest is sometimes used to flavour pastries. With a bit of chili, the lime is often served with Reunionese dishes and Caribbean ti-punch cocktails. In addition to its culinary importance, the Lime tree is also a medicinal plant whose therapeutic properties, used for centuries in traditional medicine, are now the subject of in-depth scientific studies.  Limes are less rich in ascorbic acid (Vitamin C), as well as vitamins A and B, compared to lemons. Easy to store, this citrus fruit was once embarked on sailing ships, providing a good source of vitamins to fight scurvy.

Like all Citrus trees, the Mexican Lime tree contains essential oil pockets in its leaves, flowers, and fruits, often visible to the naked eye. These can be extracted through distillation (flowers and leaves) or pressing (zest) to obtain essential oil with rebalancing properties, slightly sedative, that help realign vital energies. Stimulating, the essential oil is known to facilitate blood circulation. The fragrance of the essential oil is described as fresh, lemony, tangy, with slightly sweet and bitter notes.

Most citrus trees thrive in open ground in Mediterranean coastal regions where they find the necessary warmth all year round. But to fruit well, they require an adequate supply of water and nutrients. The Mexican Lime is self-fertile, meaning that a single individual is sufficient for complete pollination and fruiting.