The weeping willow is probably the best known willow species, and is very widely planted as an ornamental tree. It's easily identified by its distinctive, flexible, drooping branches. This Chinese native is generally found in tree rather than shrub form, and tends to grow near bodies of water. Its narrow leaves are generally 3 to 5 inches long, and taper equally at each end.
The black willow gets its name from its dark gray to nearly black bark. It's one of the most widespread North American willow species. The black willow's leaves have a narrow shape, similar to the weeping willow's. The black willow's leaves can be distinguished because they taper much more sharply at the stem end than the tip. Weeping willow leaves taper equally at both ends.
The pussy willow is best known for its silvery catkins (a cylindrical flower cluster) that are often used in decorative floral displays. The pussy willow is native to Europe and Asia and grows in both tree and shrub form. Unlike many other species of willow that have lance shaped leaves, the pussy willow's leaves have oval shapes.
As its name suggests, the crack willow's most distinctive feature is its fragile twigs that easily break off. This native to Asia and Europe is similar in appearance to the black willow, but has visible circular glands at the junctions of its leaves and stems. These glands are not found in the black willow.