Poinsett, Joel Roberts (poinˈsĕt) [key], 1779–1851, American diplomat and politician, b. Charleston, S.C. In 1810 he was sent as a special commissioner to South America to investigate political conditions of the countries struggling for independence. He served in the South Carolina legislature, was a member of the U.S. House of Representatives (1821–25), and later was minister (1825–29) to Mexico. A strong opponent of nullification, he was Secretary of War (1837–41) under Martin Van Buren. He introduced the flowering plant called the poinsettia (named after him) into the United States.
See biography by J. F. Rippy (1935, repr. 1972).