A hybrid of white and brittle willow growing in the Charles River floodplain. White willow is native in Europe and West Siberia. On most of its European area it has been hybridizing with brittle willow introduced there from Asia Minor. As a result of introgressive hybridization, white willow has lost its identity in West Europe. The widespread hybrid, taken by the Europeans for pure brittle willow, was introduced to the US under that name and then escaped from cultivation, though does not seem to be invasive in Massachusetts. The crown of this tree is mostly rounded--much like a brittle-willow crown and not like that of white willow.