Dwarf Willow on Rock - Greenland
Salix herbacea (Dwarf Willow, Least Willow or Snowbed Willow) finds the equivalent of a sunbed on some exposed rock. The rock provides extra warmth which it retains from the sun so the tree (as it strictly speaking is even though it only a few inches/cm high) spreads its leaves over the surface to make the most of the short spring and summer months.
Trees such as these are often decades old, probably well over 50 years in the case of this tree with it's relatively broad trunk.
Photo; © Paul Ward - These are pictures taken while travelling in Eastern Greenland in the Arctic summer.