The West Indian or Mexican lime is the kaghzi nimbu (numerous modifications and other local names) of India, the limûn baladi of Egypt, the doc of Morocco, the Gallego lime of Brazil, and limon corriente in some Latin American counties. The species spread westward through the Middle East and Mediterranean before being introduced to the Americas by Spanish explorers in the late 15th century. It became widely established in the Caribbean, Mexico, and Central America, where it remains the dominant lime. The name “Key lime” derives from its historic cultivation in the Florida Keys. Fruit very small, round, obovate or short-elliptical; base usually rounded but sometimes with slight neck; apex also rounded but usually with small, low, and faintly furrowed nipple. Moderately seedy and highly polyembryonic. Rind very thin; surface smooth, leathery; tightly adherent; color greenish-yellow at maturity, following which it drops from the tree. Segments 10 to 12; axis very small and usually solid. Flesh color greenish-yellow; fine-grained, tender, juicy; highly acid with distinctive aroma. Somewhat everbearing but crop comes mainly in winter (earlier in very hot climates). Tree medium in vigor and size, spreading and bushy with numerous, slender, willowy fine-stemmed branchlets densely armed with small, slender spines. Foliage dense and consists of small, pale green, broadly lanceolate, blunt-pointed leaves with definitely winged petioles. Flower buds and flowers small, and flowering occurs throughout year but mainly in spring and late summer. Not withstanding contrary statements in the literature, the new shoot growth is faintly purple-tinted and flower buds and young flowers faintly purple-tinged. Coloration fades rapidly, however, especially if the weather is warm, and is soon lost. Very sensitive to cold. Because they produce distinctive symptoms when infested with the tristeza virus, West Indian lime seedlings are widely used as an indicator in the detection of this disease.