  Vertically vibrated rod-shaped granular materials confined to quasi-2D
containers self organize into distinct patterns. We find, consistent with
theory and simulation, a density dependent isotropic-nematic transition. Along
the walls, rods interact sterically to form a wetting layer. For high rod
densities, complex patterns emerge as a result of competition between bulk and
boundary alignment. A continuum elastic energy accounting for nematic
distortion and local wall anchoring reproduces the structures seen
experimentally.
