The New World is exceedingly rich in species of plants employed in primitive societies for their hallucinogenic or other psychoactive effects. They are found amongst the fungi and the angiosperms. Only a selected few are here considered - those of greatest importance from the point of view of use or of botanical rarity or historical significance. In this iconography, only species of the flowering plants are considered. It is interesting to note that the New World is much richer in species employed as hallucinogens than the Old World. There are probably 150 species (including fungi) so used in primitive societies in the Americas, and additions to the list are frequently being discovered as ethnobotanical field studies, especially in the tropical regions, progress. In any consideration of hallucinogenic plants it is essential to remember that primitive societies believe these psychoactive plants to be the "medicines" par excellence, and that their unusual activity which puts man in contact with the spirit world from which comes all death and illness, is due to a resident spirit or divinity. They are considered sacred medicines, not to be abused or taken merely for pleasure. The enumeration of the families follows the Engler-Prantl system.