Coca is any of the four cultivated plants in the family Erythroxylaceae, native to western South America. Coca is known worldwide for its psychoactive alkaloid, cocaine. Coca leaves contain cocaine which acts as a mild stimulant when chewed or consumed as tea, with slower absorption than purified cocaine and no evidence of addiction or withdrawal symptoms from natural use.

The coca plant is a shrub-like bush with curved branches, oval leaves featuring distinct curved lines, small yellowish-white flowers that develop into red berries. Genomic analysis reveals that coca, a culturally and economically important plant, was domesticated two or three separate times from the wild species Erythroxylum gracilipes by different South American groups during the Holocene. Chewing coca in South America began at least 8,000 years ago, as evidenced by coca leaves and calcite found in house floors in Peru's Nanchoc Valley, suggesting early communal use alongside the rise of farming. Coca use evolved from a sacred and elite ritual to widespread use under Inca rule. The Incas deeply integrated coca into their society for labor, religion, and trade, valuing it so highly that they colonized new lands to cultivate it. Despite later Spanish attempts to suppress its use, even they relied on it to sustain enslaved laborers. Coca leaves have been traditionally used across Andean cultures for medicinal, nutritional, religious, and social purposes—serving as a stimulant, remedy for ailments, spiritual tool, and source of sustenance—especially through chewing and tea.

Coca thrives in hot, humid environments, with harvesting occurring multiple times a year from plants grown in carefully tended plots. The plant is grown as a cash crop in the Argentine Northwest, Bolivia, Alto Rio Negro Territory in Brazil, Colombia, Venezuela, Ecuador, and Peru, even in areas where its cultivation is unlawful. There are some reports that the plant is being cultivated in the south of Mexico, by using seeds imported from South America, as an alternative to smuggling its recreational product cocaine. It also plays a fundamental role in many traditional Amazonian and Andean cultures as well as the Sierra Nevada de Santa Marta in northern Colombia. Coca leaves are commercially and industrially used in teas, foods, cosmetics, and beverages, with growing political and market support in countries like Bolivia and Peru, despite restrictions in others like Colombia. The international prohibition of coca leaf, established by the 1961 United Nations Single Convention despite its traditional use in Andean cultures, has been widely contested—particularly by Bolivia and Peru—leading to ongoing efforts, including a 2025 WHO review, to reevaluate its legal status based on cultural and scientific grounds. Coca leaf is illegal or heavily restricted in most countries outside South America, treated similarly to cocaine, with limited exceptions for scientific or medical use and a few authorized imports, such as in the U.S. for Coca-Cola flavoring.

The cocaine alkaloid content of dry Erythroxylum coca var. coca leaves was measured ranging from 0.23% to 0.96%. Coca-Cola used coca leaf extract in its products from 1885 until about 1903, when it began using decocainized leaf extract. Extraction of cocaine from coca requires several solvents and a chemical process known as an acid–base extraction, which can fairly easily extract the alkaloids from the plant.

The coca plant resembles a blackthorn bush, and grows to a height of 2 to 3 m (7 to 10 ft). The branches are curved, and the leaves are thin, opaque, oval, and taper at the extremities. A marked characteristic of the leaf is an areolated portion bounded by two longitudinal curved lines, one line on each side of the midrib, and more conspicuous on the under face of the leaf.

The flowers are small, and disposed in clusters on short stalks; the corolla is composed of five yellowish-white petals, the anthers are heart-shaped, and the pistil consists of three carpels united to form a three-chambered ovary. The flowers mature into red berries.

The leaves are sometimes eaten by the larvae of the moth Eloria noyesi.

There are two species of coca crops, each with two varieties: