Japanese raspberry (Rubus parvifolius L.) is native to eastern Asia and Australia and has naturalized in several locations in Illinois, Iowa, Massachusetts, Missouri, and Ohio. This species was introduced in North America for food and erosion control, but it appears to be becoming a serious invasive species threat in savannas and prairies. It was found in a former commercial game-hunting farm on Walnut Creek National Wildlife Refuge (now Neal Smith National Wildlife Refuge) in 1991, and was identified as Japanese raspberry in 1995. Japanese raspberry grows vigorously and spreads via rooting from low-arching-to-prostrate canes that are up to 300 cm long, and its seeds can be dispersed by birds. In summer, primocanes are green to purplish green, though they turn reddish brown in winter. It has small pink flowers and bright red fruits. It thrives in shade in a remnant savanna on the refuge, forming rapidly expanding near-monoculture populations. Efforts to control it with herbicide treatment since its discovery have been unsuccessful, but also somewhat sporadic. A second population in a roadside within a mile of the refuge demonstrates its ability to thrive in full sun. County dredging of ditches for drainage improvement may be serving as a vector for its expansion.