Salix glauca is one of the most common willows in Denali occurring in numerous habitats including gravel bars, spruce forest, subalpine slopes and even dotting tundra in some areas. Salix glauca is a highly variable, erect shrub up to 5 m tall, with leaves with pale undersides and late-developing white-wooly catkins. Branches are reddish brown to grayish and variably pubescent. Leaves are oblanceolate, dark green above, glaucous and densely hairy beneath. The yellowish petioles are 2-15 mm long. Leaf margins are entire. Stipules are linear and small (not persistent). Willows are dioecious (that is, individual plants produce either male or female flowers), the flowers highly reduced and borne in catkins specialized for wind pollination. Catkins are born on leafy branches, developing with or a little after the leaves. Pistils are densely white-hairy and have 4 long, dark stigmas. Salix glauca is often confused with S. niphoclada, but that species has shorter petioles, the stipules are almost absent, and the leaf tips are usually not pointed.
Salix glauca is one of the last willows to flower. Catkins appear with or soon after the leaves and remain on the plant over winter, releasing seeds the next spring (Collett 2004).
Salix glauca is dioecious, and insect and wind pollinated. Seeds have attached hairs to aid in wind dissemination. It also readily spreads vegetatively.
Collett (2004) documented a variety of insects that utilize S. glauca including gall-formers such as: Rabdophaga spp., Euura sp., Pontia sp, and eriohyid mites, and a moth leaf-miner. Micrurapteryx salicifoliella. This species is the host plant for the torticid moth Acleris arcticana.
Like all willows, the fresh bark of S. glauca contains salicin, a precursor to aspirin and has traditionally been used as pain and fever reliever.
Salix glauca is a circumpolar species complex with numerous subspecies and races with a widespread distribution ranging across northern Eurasia, northern North America and Greenland. In North America, this species ranges from Alaska across Canada to the Atlantic and south into the Pacific Northwest and Rocky Mountain states south to New Mexico. In Alaska, this species is common and widespread in suitable habitats statewide, except the southeastern panhandle. In Denali, S. glauca is common and locally abundant park-wide on both sides of the Alaska Range crest.
Salix glauca is a subalpine species found over a large range of elevations in the park (122 m to 1466 m) with the average plot elevation at 773 m. This species shows a slight preference for steeper (>20 degree) south facing slopes.