Salix petrophila

Salix petrophila, commonly known as alpine willow and Rocky Mountain willow, is a Northwest American mountain shrub in the willow family (Salicaceae).

Habitat and range
It can be found in the subalpine zone and alpine zone of the Sierra Nevada range in wetlands such as moist banks and wet meadows, up to 9900 to 13000 ft.

Growth pattern
It is often overlooked because although sprawling and mat-forming, it is very small for a shrub, growing to only 4 in tall.

Leaves and stems
Leaves are 3/4 to 1+3/4 in long, elliptic, with soft hairs on the surface when young. The other mat forming Sierra Nevada alpine willow, Salix nivalis, has smaller leaves (1/4 to 7/8 in that are hairless when young.

Inflorescence and fruit
Each plant has either all male or all female flowers, with an inflorescence that is a dense, upright catkin, growing to 2 in.

Ecological interactions
It is pollinated by ants, as are some other willows.