The Dwarf Willow (Salix herbacea - also known as the Least Willow) is the commonest of a group of tiny creeping willows in the willow family (Salicaceae). They are adapted to survive in harsh sub-arctic environments, and as such are widespread throughout Europe, from the Pyrenees in the west to Bulgaria in the east. They can also be found elsewhere, such as in Canada. They are a mountain willow, and can usually be found in rocky moorland over 600 m high.

They typically grow to only 1-5 cm in height and have round, shiny green leaves. Like the rest of the willows, Dwarf Willows are dioecious, which means that they produce both male and female catkins. As a result the plant's appearance varies; the female catkins are red-coloured, while the male catkins are yellow-coloured.