Salix herbacea aka Dwarf Willow

Salix herbacea is a dwarf willow in the Salicaceae family. It has two common names: least willow and dwarf willow. It grows in subarctic North America and cold parts of Europe. In Europe, it also grows high in the mountains. It is native to Britain and Ireland. This shrub sheds its leaves and forms a low mat. Its stems creep and twist as they grow.

Garden plants reach about 0.33 feet (0.1 m) tall. They spread 0.33–1.64 feet (0.1–0.5 m) wide. Virginia Tech reports plants just 0.08 feet (0.025 m) tall. Much of their growth lies under the ground. Some reach nearly 0.42 feet (0.127 m). The stems bear two or three small leaves. These range from round to broadly oval and have clear veins. Blunt teeth line their edges. Their bases may have a heart shape. The tops shine green, while a pale coat covers the undersides. Young stems range from yellow-brown to red-brown, then turn gray. The round, reddish-brown buds each have one scale.

Small flowers open in spring, with or just after new leaves. Male and female flowers grow on separate plants. They form upright clusters called catkins at the stem tips. The flowers start with a red tint. Male flowers turn yellow as their pollen ripens. Female plants then form pointed seed capsules, which turn red. These release small, silky seeds early in the growing season. Wind carries the seeds away.

Grow this willow in full sun and deep soil. Keep the soil moist, but let excess water drain away. It grows in clay, loam, and sand. The soil may be acidic, neutral, or alkaline. Avoid shallow chalk soils. It copes with cold and exposed sites and with sheltered gardens. The RHS gives it an H7 hardiness rating. This covers Europe's coldest inland climates, below −20°C. Plants reach their full size in two to five years. Take softwood cuttings in early summer or hardwood cuttings in winter.

Its low form suits rock gardens and ground cover. The RHS also lists gardens by the coast and in courtyards. It lists cottage and wildlife gardens, too. Pests that may attack it include aphids and caterpillars. Willow leaf beetles, sawflies, and willow scale insects may occur too. Diseases may include willow anthracnose, honey fungus, and rust. The supplied sources give no guidance specific to this species on safe use as food or its toxicity.