Dusky willow (Salix melanopsis) has long, narrow, hairless leaves. In general, willows are notoriously hard to identify–mostly because different species interbreed. Despite this confusion, it’s generally easy to tell when you’re looking at some species of willow. They can be shrubs or trees, but they often are found in wet areas–on the edge of wetlands, or along stream banks. They tend to have slim limbs. Most notably they sport small, rounded mini-leaves (stipules) thatgrow at the base of the larger leaf’s stalks. All willows have leaves that are alternate and in the spring they sprout silky catkins.
Willows have a lot of salycilic acid, which is essentially aspirin. You can buy willow bark capsules at health food stores as a more natural alternative painkiller.