kudzu (kŏdˈzō) [key], plant of the family Leguminosae (pulse family), native to Japan. Kudzu ( Pueraria thunbergiana ) has a woody stem, broad leaves, and clusters of large purple flowers. It is used as a cover crop, for pasturage and hay, and for controlling soil erosion; in Asia, it is cultivated for its edible tubers and hemplike fiber. It was introduced in the United States c.1876 as a decorative vine and is now escaped from cultivation in the South, where it has become a noxious weed. Kudzu is classified in the division Magnoliophyta, class Magnoliopsida, order Rosales, family Leguminosae.