Salix fragilis can grow to be a large tree, often dividing into several large branches low on the trunk, or even at the ground level. The bark becomes deeply furrowed in mature trees. It is a common site along streams and on the many disturbed, moist soils around cities and towns. Salix fragilis is often mistakenly misidentified as Salix nigra. Leaves of S. fragilis are usually glaucous (whitened) beneath and lack stipules, compared to S. nigra whose leaves are not whitened beneath and often have stipules at the base of the petiole.

Salix fragilis is an introduced species that has become thoroughly naturalized in wet, sunny sites (once established in the open, the forest can grow up around it or with it, but it is rare to see successful seedlings under canopy). It is the commonest tree willow in Wisconsin. It is found mostly in the southern half of the state, but extends north along Green Bay to Marinette County and in a few locations along the Wisconsin River north to Lincoln and Taylor Counties.