Salix pentandra can be a shrub (shown above) or a small tree. The leaves are simple, alternate and toothed. The leaves are green beneath, not glaucus (though often lighter in color than the upper surface), and there are sometimes small stipules at the base of the blade, but they are often deciduous by the time the fruit matures.

Salix pentandra is cultivated and rarely escapes in Wisconsin. It is most likely to be confused with Salix lucida for which the leaves tend to be more strongly attenuate, leaves on the flowering branches are toothed and the mature capsules often dehisce (open) in June. Salix pentandra leaf tips are less strongly attenuate, margins of leaves on the pistillate flowering branches are entire or nearly so and the capsules open after the first of July.

The willow species are quite variable and difficult to distinguish and any "shortcuts" around the proven keys are likely to result in frequent errors. See the key to willows for helpful characters to identify the species, or try the more thorough keys in Michigan Flora vol 2.