Vallisneria × pseudorosulata S. Fujii & M. Maki is an invasive aquatic weed that has recently become a major issue within the U.S. Southeast. Vallisneria × pseudorosulata is a hybrid between two nonnative eelgrass species (Vallisneria spiralis L. and Vallisneria denseserrulata Makino) and has rapidly overtaken water bodies in Tennessee, Alabama, and Florida. This hybrid can reproduce rapidly through offshoot formation and floating propagules capable of drifting large distances before establishing. Vallisneria × pseudorosulata has been previously found in Japan and is thought to have been introduced in the United States by the aquarium trade or through dumping.
