UPAS  , a Javanese word meaning

poison, and specially applied to the poison derived from the gum of the anchar tree (Antiaris toxicaria), a member of the fig-family (Moraceae), and a native of the Sunda Islands, which was commonly used to envenom the darts of the natives . The name of the upas tree has become famous from the mendacious account (professedly by one Foersch, who was a surgeon at Samarang in 1773) published in the London Magazine, December 1783, and popularized by Erasmus Darwin in " Loves of the Plants " (Botanic Garden, pt. ii.) . The tree was said to destroy all animal life within a radius of 15 M. or more . The poison was fetched by condemned malefactors, of whom scarcely two out of twenty returned . All this is pure fable, and in good part not even traditional fable, but mere invention . The milky juice of the tree contains an active principle named antiarin, which has been recommended as a cardiac stimulant . It is without any properties, however, that entitle it to clinical employment . The tree is described as one of the largest in the forests of Java, the straight cylindrical stem rising without a branch to the height of 6o to 8o ft . It has a whitish bark and on being wounded yields plentifully the milky juice from which the poison is prepared . For a full account of the tree, see Bennett and Brown, Plantae Javanicae rariores, p . 52 (1838) .