This tall rhizomatous herb has become a widespread weed across temperate North America. In Ky. it is especially common along some Appalachian streams and rivers on medium-acid soils. Sight records of SE are mapped here as open dots. R. japonica and the intergrading sachalinensis comprise a polyploid complex (2n = 44 ro 132). The generic assignment of those two species remains controversial; Reynoutria may best be merged with Fallopia (as reviewed by W). Young shoots of these plants are reported to be traditionally eaten in Japan, often pickled in salt mixed with magnesium chloride (Wikipedia 14 Feb 2019). Simple cooking may be possible, but deterrent chemicals can be a problem (C. Rasp, pers, comm.); these include sourness in oxalic acid, plus the emetic anthraquinone, emodin (Jayasuriya et al. 1992). Various other chemicals with medicinal potential have been reported (Barney et al. 2006), including high content of the stilbenoid, resveratrol, in roots (Chen et al. 2013). Despite its challenging phytochemistry, the species is reportedly palatable to livestock in general (Barney et al. 2006).