Salix fuscescens is a creeping perennial dwarf to low willow shrub, which is relatively common in wet bogs and fens in the boreal lowlands on both sides of the Alaska Range crest in Denali. The branches creep and spread in moss with many adventitious roots occurring along the reddish-brown, shiny glabrous stems and branches. Leaves are obovate to elliptic in shape, toothed at the base, broadest towards the slightly pointed tip, glossy dark green above, and glaucous beneath. There are no stipules. Willows are dioecious (separate plants producing either male or female flowers), the flowers highly reduced and borne in catkins. Female catkins develop at the same time as the leaves, produced on leafy peduncles. Pistils are reddish and covered with short hairs. Fruits are capsules that split open by two valves to release many hairy seeds. This willow can be identified by its creeping habit, leaves toothed at the base, and fondness for very wet habitats.

Salix fuscescens typically flowers in early summer (mid-May). Seeds are disseminated mid-July.

S. fuscescens is dioecious. Flowers are wind and insect pollinated. Seeds have attached hairs to allow wind dispersal.

S. fuscescens grows in bogs, fens, and sedge meadows. Soil pH for sites in the park where S. fuscescens was found ranged from 3.5 to 5.5 with an average pH of 4.6.

Wet sites, obligate wetland species.