Heracleum mantegazzianum is native to Asia and has been introduced into Europe and North America. It is characterised by its size and may grow to 4.5 to 6 metres in height. It is most common along roadsides, vacant lots, streams and rivers, and can be considered an invasive freshwater weed. It forms a dense canopy, out-competing native riparian species and results in an increase in soil erosion along the stream banks where it occurs. Heracleum mantegazzianum germinates from early spring throughout the growing season, after exposure to winter temperatures. H. mantegazzianum exudes a clear watery sap that sensitises the skin to ultraviolet radiation which can result in severe burns. Populations in urban and suburban areas represent an increasing public health hazard. Glyphosate is considered the most effective herbicide.