Butomus umbellatus established in Massachusetts.
Butomus umbellatus (Butomaceae), flowering rush, is an emergent, perennial, wetland species of lake margins or slow-moving waterways. During a 2006 floristic inventory related to a weed management project, Butomus was first observed in Massachusetts, USA, flowering on the western shore of the eastern basin of Winter Pond, Middlesex Co., Winchester (GeoSyntec 2006). Sterile specimens were later vouchered in 2008 from the north shore of the same basin and serve as the first collection. After a few unrelated pond assessments (2016 and 2017) failed to note individuals, a July 2019 shoreline survey documented the species' successful establishment around most of the eastern basin's ("Little Winter Pond") periphery, where plants were flowering at multiple locations. In 2010, a B. umbellatus population was also observed at the Saugus Iron Works, a National Historic Site managed by National Park Service. This is thought to be the first report of the occurrence of B. umbellatus in Massachusetts, USA.