Khat (Catha edulis Forsk., Celastracae) is a flowering evergreen tree that grows in parts of eastern Africa and the southwestern highlands of Arabia. Its young leaves and tender stem tips, also called khat, are stimulating and produce a mild euphoria when chewed and their juices ingested. Khat has various psychostimulant alkaloids, of which the main one, cathinone, is amphetamine related and highly unstable. Khat leaves and shoots contain various alkaloids, of which cathinone and cathine are the primary and secondary active ingredients in stimulating the central nervous system. As with other psychoactive plants, the effects of the active constituents differ from one specimen to another according to the cultivar’s size, age, health, and the site conditions of growth, such as exposure, soil, soil moisture, and drainage.

Most of the world’s khat is grown in Yemen, Ethiopia, and Kenya, where its use is long established. Khat is a major import of Somalia and Djibouti, and demand in both countries far exceeds domestic production. During the past half-century, the number of users has increased substantially, and emigrants from the khat-chewing countries have introduced (on a small scale) the use of the drug to some countries in Europe and North America.

International trade in khat is a multimillion-dollar business in the Horn of Africa and southwestern Arabia. Daily consumption of the drug is estimated to be about 5 million portions of khat (Kalix 1994: 69), or about 500,000 kilograms of the leaf material chewed. The various estimates of the total number of regular users range from 3 to 6 million. Methcathinone, a synthetic, white, chunky powder, known in the United States by the street name “cat,” is a substance very dissimilar from khat.