The Collaborative International Dictionary of English v.0.48:

Bunch grass \Bunch" grass`\ (Bot.)
   A grass growing in bunches and affording pasture. In
   California, Atropis tenuifolia, Festuca scabrella, and
   several kinds of Stipa are favorite bunch grasses. In Utah,
   Eriocoma cuspidata is a good bunch grass.
   [1913 Webster]