Jalap is a cathartic drug consisting of the tuberous roots of Ipomoea purga, a convolvulaceous plant growing on the eastern declivities of the Sierra Madre Oriental of Mexico at an elevation of 5000 to 8000 ft. above sea level, more especially about the neighbourhood of Chiconquiaco on the eastern slope of the Cofre de Perote in the state of Veracruz.