COCA, or Cuca (Erythroxylon coca), a plant of the natural order Erythroxylaceae, the leaves of which are used as a stimulant in the western countries of South America.  It resembles a blackthorn bush, and grows to a height of 6 or 8 ft. The branches are straight, and the leaves, which have a lively green tint, 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, are of a deep green on the upper, and a 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. Bad specimens have a camphoraceous smell and a brownish colour, and lack the 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 seeds are sown in December and January in small plots (almacigas) sheltered from the Sun, and the young plants when from 1 to 2 ft. in height are placed in holes (aspi), or, if the ground is level, in furrows (uachos) in carefully-weeded soil. 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 gathered from plants varying in age from one and a half to upwards of forty years. They are considered ready for plucking when they break on being bent. The first and most abundant harvest is in March, after the rains; the second is at the end of June, the third in October or November. The green leaves (matu) 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 of the leaves, must be kept from damp.
In the Kew Bulletin for January 1889 is an account of the history and botany of the plant, which has been so long under cultivation in South America that its original home is doubtful. As the result of this cultivation numerous forms have arisen. The writer distinguishes from the typical Peruvian form with pointed leaves a variety novo-granatense, from New Granada, which has smaller leaves with a rounded apex. The plant is now cultivated in the West Indies, India, Ceylon, Java and elsewhere. It has been estimated that coca is used by about 8,000,000 of the human race, being consumed in Bolivia, Peru, Ecuador, Colombia and Rio Negro. In Peru the Indians carry a leathern pouch (the chuspa or huallqui) for the leaves, and a supply of pulverized unslaked lime, or a preparation of the ashes of the quinoa plant (Chenopodium Quinoa), called llipta or llucta. Three or four times a day labour is suspended for chacchar or acullicar, as the mastication of coca is termed. The leaves, deprived of their stalks, are chewed and formed into a ball (acullico) in the mouth; a small quantity of the lime or llipta is then applied to the acullico to give it a proper relish. Two or three ounces of coca are thus daily consumed by each Indian.
Coca was used by the Peruvian Indians in the most ancient times. It was employed as an offering to the Sun, or to produce smoke at the great sacrifices; and the priests, it was believed, must chew it during the performance of religious ceremonies, otherwise the gods would not be propitiated. Coca is still held in superstitious veneration among the Peruvians, and is believed by the miners of Cerro de Pasco to soften the veins of ore, if masticated and thrown upon them.
The composition of different specimens of coca leaves is very inconstant. Besides the important alkaloid cocaine (q.v.), occurring to the extent of about O.2% in fresh specimens, there are several other alkaloids. The preparations of coca leaves are incompatible with certain drugs which might often be prescribed in combination with them, such as salts of mercury, menthol and mineral acids, which latter decompose cocaine into benzoic acid and ecgonine.
Coca leaves and preparations of them have no external action. Internally their action is similar to that of opium, though somewhat less narcotic, and causing a dilatation of the pupil of the eye instead of a contraction. When masticated, the leaves first cause a tingling in the tongue and mucous membrane of the mouth, owing to a stimulation of the nerves of common sensation, and then abolish taste owing to a paralysis of the terminals of the gustatory nerves. They have a definite anaesthetic action upon the mucous membrane of the stomach, from which there come in large part those organic sensations which we interpret as hunger. Hence it is possible, under the influence of coca, to go without food or consciousness of needing it, for as long a period as three days. The drug is not a food, however, as its composition and history in the body clearly show, and the individual who comfortably fasts under its influence nevertheless shows all the physical signs of starvation, such as loss of weight. In small doses coca stimulates the intestinal peristalsis and thus is an aperient, but in large doses it paralyses the muscular coat of the bowel, causing constipation, such as is constantly seen in coco-maniacs, and in those inhabitants of Peru and the adjacent countries who take it in excess or are markedly susceptible to its influence.
The injection of coca leaves has a very remarkable effect upon the higher tracts of the nervous system - an effect curiously contrary to that produced by their chief ingredient upon the peripheral parts of the nervous apparatus. The mental power is, at any rate subjectively, enhanced in marked degree. In the absence of extended experiments in psychological laboratories, such as have been conducted with alcohol, it is not possible to say whether the apparent enhancement of the intellect is an objectively demonstrable fact. The physical power is unquestionably increased, such muscular exercises as are involved in ascending mountains being made much easier after the chewing of an ounce or so of these leaves. Excess in coca-chewing leads in many cases to great bodily wasting, mental failure, insomnia, weakness of the circulation and extreme dyspepsia.
 Garcilasso de la Vega, writing of the plant, says that it is called cuca by the Indians, coca by the Spaniards; and Father Blas Valera states that the leaves are called cuca both by Indians and Spaniards (The Royal Commentaries of the Yncas, 1609-1617; trans, by C. R. Markham, Hakluyt Soc., 1871). See also, on the name cuca, Christison, Brit. Med. Journ., April 29, 1876, p. 527.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)