COCA or CUCA (Erythroxylon Coca), a plant of the family Erythroxylaceae, the leaves of which are used as a stimulant in western South America. It resembles a blackthorn bush, and grows to a height of 8 feet. The branches are straight and the lively green leaves are thin, opaque, oval, more or less tapering at the extremities. A marked characteristic of the leaf is an areolated portion bounded by two longitudinal curved lines one on each side of the midrib, and more conspicuous on the under face of the leaf. Good samples of the dried leaves are uncurled, deep green on the upper, and grey-green on the lower surface, and have a strong tea-like odour; when chewed they produce a sense of warmth in the mouth, and have a pleasant, pungent taste. The flowers are small, and disposed in little 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 are succeeded by red berries. The plants thrive best in hot, damp situations, such as the clearings of forests ; but the leaves most preferred are obtained in drier localities, on the sides of hills. The leaves are considered ready for plucking when they break on being bent. The green leaves (mate) are spread in thin layers on coarse woollen cloths and dried in the sun; they are then packed in sacks, which, in order to preserve the quality must be kept from damp. The corn position of different specimens of coca leaves is very inconstant. Besides the important alkaloid cocaine (q.v.) there are several other alkaloids. Coca leaves and preparations of them have no external action. Internally their action is similar to that of opium, though less narcotic.