least willow

noun3

1. •
   Either of two species of willow.
2. •
   Salix herbacea, a tiny creeping shrub widely distributed in alpine and Arctic environments.

   • The leaves of the least willow (S. herbacea), soaked in water, are employed in Iceland for tanning leather. — 1848
3. •
   Salix rotundifolia, a densely matted shrub growing in tundral regions.

   • Least willow is found in alpine and arctic tundra in a variety of vegetation types from dry scree to cool, wet slopes. — 2010