C. aurantifolia, is known by many names such as Key lime, Bartenderís lime, and West Indian lime.
The trees are moderately-sized and bushy, almost shrub-like, and the leaves are distinctively aromatic when crushed. Mexican lime trees are sensitive to cold. The blossoms are pure white and fragrant. The fruits are small, approximately one and one-half inches in diameter, and almost round, with a thin, smooth, greenish-yellow rind at maturity that is especially fragrant. The flesh is greenish-yellow, seedy, and highly acidic, with a fine texture. Once Mexican limes reach full maturity, usually in autumn to early winter, they drop from the tree.
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.