This aquatic species has been widely established in North America and it has often escaped, becoming a locally abundant weed. The first report from Ky was made ca. 1940 (M). There has been nomenclatural confusion with the closely related M. sibiricum Komarov. (= M. exalbescens Fern.), which is native across northern and western North America, but unknown in Ky. and most southeastern states (Cr, K, W) or perhaps recently adventive in Mo. (Ladd & Thomas 2019).