Flower:

Male and female flowers are on separate plants (dioecious) in spike-like clusters (catkins) from buds along 1 year old branches, emerging before the leaves. Male catkins are ½ to 1½ inches long, the flowers densely to somewhat loosely packed, each flower with 2 purple to yellow-tipped stamens. Female catkins are 2/3 to 3½ inches long, the flowers moderately crowded on the spike, cone-shaped with a gradual taper to the beak, hairless, and on slender stalks mostly less than 1 mm long, occasionally to 3 mm long. At the base of each male and female flower stalk is a tiny, dark brown to black scale-like bract covered in straight white hairs.

Leaves and stems:

Leaves are alternate, 1½ to 4½ inches long, ½ to 2 inches wide, 1.4 to 3 times as long as wide, egg-shaped to oval-elliptic, widest below, at or above the middle, usually pointed at the tip, rounded to somewhat heart-shaped at the base, finely toothed around the edges with rounded teeth and often a bit wavy. The upper surface is dull to slightly glossy dark green with a few hairs along the midvein, the lower surface paler green and hairless. Leaf stalks are commonly red.

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 ¾ inch long. New leaves are sparsely to moderately hairy and typically red-tinged, becoming mostly hairless with age. New branchlets are hairy and yellowish to reddish, turning reddish to brown and hairless the second year. Stems are multiple from the base, have smooth to slightly rough gray bark and can reach 1+ inches diameter. Branches are numerous and leafy.

Fruit:

The spike elongates some as fruit matures, the fruit becoming more loosely arranged than the flowers. Fruit is a capsule 4 to 7 mm long, yellowish to reddish when mature, hairless, conical to horn-shaped with a gradual taper to the beak. The capsule splits into two halves when mature, releasing the cottony seed.

Notes:

There are over 20 species of Willows in Minnesota; False Mountain Willow is one of the least common, a medium to tall shrub found mostly in high quality shrub swamps and brush prairies. According to the DNR, it was first recorded in 1939 along the St. Louis River near Fon du Lac, but wasn't correctly identified until 1993. The original population was never relocated but another was discovered several years later nearby in Carlton County. A handful of additional sites were discovered in the northwest counties, which appear to be continuous with Canadian populations, where the St. Louis River sites are apparently disjunct. Its ecological requirements are not well understood, but the brush prairies where it is most often found have suffered habitat destruction and degradation from agriculture, pollution and invasive species, and may be at least partly responsible for its rarity in Minnesota. It was listed as a Special Concern species in 2013.

False Mountain Willow is recognized by its large, persistent stipules; leaves that are relatively broad (for a willow), toothed, rounded to slightly heart-shaped at the base, mostly hairless, paler green to gray-green on the underside and typically with red leaf stalks; hairless fruit 4 to 7 mm long; catkins emerging before the leaves; male flowers with 2 stamens. Both male and female flowers are subtended by a brown to black bract covered in straight white hairs.

The only other Willow with such large stipules is Missouri River Willow (Salix eriocephala), which is found in a wider variety of wetlands nearly statewide, has narrower leaves up to 6 inches long, leaf stalks are typically green, and the capsules more pear-shaped with a more abrupt taper at the tip, where False Mountain Willow capsules are more evenly tapered to the pointed tip. Balsam Willow (Salix pyrifolia) has leaves similar to False Mountain Willow, but has very small stipules.