Real Dictionary

crown vetch in American English
a European plant (Coronilla varia) of the pea family, with pink and white flowers: sometimes cultivated in the U.S. as a ground cover, esp. along highways
noun: a plant, Coronilla varia, of the legume family, native to the Old World, having clusters of pink flowers and used to prevent erosion on banked roadsides

crown vetch in British English
noun: a trailing leguminous European plant, Coronilla varia, with clusters of white or pink flowers: cultivated in North America as a border plant