lime, in botany, small shrublike tree ( Citrus aurantifolia ) of the family Rutaceae (rue family), one of the citrus fruit trees, similar to the lemon but more spreading and irregular in growth. The true lime, a natural hybrid of the citron and papeda, is native to SE Asia and has been introduced into S Europe, the West Indies, Mexico, Florida, and California. Chief production is in tropical regions of the Old and New World; most true limes in American commerce, often known as Key or Mexican limes, come from Mexico or the West Indies. The lime is the most susceptible to frost injury of all citrus fruits, but some varieties do well in sandy or rocky soils usually unfavorable to citrus.
The bright green fruit is smaller than the lemon, more globular, more acid, and with a thinner rind. It has the vitamin value and other properties of the citrus fruits. The juice has long been known as a preventive against scurvy and is one of the main sources of citric acid.
The predominant lime in American cuisine is a larger, more mildly flavored, typically seedless cross, C. latifolia, between the true lime and citron, known as a Persian, Tahitian, or Bearss lime, and there are a number of other citrus fruits called limes. The name lime is also applied to the unrelated linden and sometimes to a species of tupelo, or sour gum, known also as the Ogeechee lime.
Limes are classified in the division Magnoliophyta, class Magnoliopsida, order Sapindales, family Rutaceae.