PALM, n. A species of tree . . . of which the familiar itching palm (Palma hominis) is most widely distributed . . . . This noble vegetable exudes a kind of invisible gum, which may be detected by applying to the bark a piece of gold or silver.
Source: The Devil's Dictionary, 1911.
-- Ambrose Bierce, (Jun 24 1842-1914), US journalist, short-story writer; He was a noted wit, satirist and sardonic short story writer who disappeared while covering the Mexican revolution.