soma (sō´mə), psychotropic plant, the juice of which was sometimes drunk as part of the Vedic sacrifice (see Veda). Many hymns in the Rig-Veda are in praise of soma. In the late Vedic period substitutes for soma came to be used, and the original plant was lost. It has recently been identified with the fly agaric mushroom, Amanita muscaria, used in Siberian shamanism.
See R. G. Wasson, Soma: Divine Mushroom of Immortality (1971).