The Collaborative International Dictionary of English v.0.48:

bristlegrass \bristlegrass\ n.
   grasses of grasslands and woodlands having large gracefully
   arching spikes with long bristles beneath each spikelet.

   Syn: bristle grass.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

bristlegrass
    n 1: grasses of grasslands and woodlands having large gracefully
         arching spikes with long bristles beneath each spikelet
         [syn: bristlegrass, bristle grass]