The Collaborative International Dictionary of English v.0.48:

Panicum \Pan"i*cum\, n. [L., panic grass.] (Bot.)
   A genus of grasses, including several hundred species, some
   of which are valuable; panic grass.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Panicum
    n 1: panic grass [syn: Panicum, genus Panicum]