Salix eriocephala, known as heart-leaved willow or Missouri River willow, is a species of willow native to a large portion of the temperate United States and Canada.
It is usually found as a narrow shrub or small tree with multiple trunks growing to a height of 20 ft (6.1 m). It has dark gray, scaly bark with thick lance-shaped leaves that are hairy underneath. The silky catkins appear before the leaves in early spring.
Male and female flowers are on separate plants (dioecious) in spike-like clusters (catkins) at the tips of very short branchlets or from buds along 1 year old branches, emerging with or just before the leaves. Male catkins are ½ to 2 inches long, the flowers densely to somewhat loosely packed, each flower with 2 yellow-tipped stamens.Leaves are alternate, 1 to 6 inches long, to 1+ inch wide, 2.3 to 8 times as long as wide, narrowly oblong to elliptic, mostly widest at or just above the middle, pointed at the tip, wedge-shaped to somewhat rounded at the base, finely toothed around the edges with rounded teeth.At the base of the leaf stalk is a pair of large, leaf-like appendages (stipules) that are rounded or pointed at the tip, up to ½ inch long. Stems are multiple from a compact crown, have smooth to slightly rough gray bark and can reach 8+ inches diameter.The spike elongates some as fruit matures, the fruit becoming more loosely arranged than the flowers.