- Name also: Myrtle Willow (USA)
- Family: Willow Family – Salicaceae
- Growing form and height: Shrub. 0.2–1 m (8–40 in.).
- Flower: Male and female flowers on separate plants. Inflorescence a hairy, short-stalked catkin, stalk leaved. Individual flowers in axils of catkin scales, small, lacking perianth. Catkin scales long-hairy, with rounded tip, those of female inflorescences blackish-red. Stamens 2, filaments hairless. Pistil formed from two fused carpels.
- Leaves: Alternate. Short-stalked, hairless or sparsely hairy, leathery, stipulate. Stipules fairly large, elliptic, margins with glandular teeth. Leaf-blade approx. 3 cm (1.2 in.) long, elliptic to obovate, glandular-toothed, green on both sides, shiny, sometimes long-hairy beneath along the veins. Vein pairs 5 to 6.
- Buds: Yellowish-brown, rounded, hairless or sparsely hairy.
- Fruit: Fairly slender, short capsule. Seeds plumed.
- Habitat: Eutrophic fens, seepage water strands, stream margins, fjeld scrub. Often on calcareous soils (calciphile).
- Flowering time: June. Flowers when coming into leaf.
Willows are insect-pollinated, sympodially growing, dioecious trees, shrubs, or dwarf shrubs. Their buds have a single protective scale, and their leaves are entire and stipulate. The inflorescence is a catkin which falls off in one piece.
Whortle-leaved willow is a demanding species as regards nutrient availability. It is a small shrub native to the northern parts of Eurasia. The flowering takes place at the emergence of the leaves. The branches of this species are thick and reddish-brown. Hybrids between willow species are common. Whortle-leaved willow crossbreeds quite commonly with gray willow (S. glauca) and dark-leaved willow (S. myrsinifolia).