The Collaborative International Dictionary of English v.0.48:
Panic \Pan"ic\, n. [L. panicum.] (Bot.) A plant of the genus Panicum; panic grass; also, the edible grain of some species of panic grass. [1913 Webster] Panic grass (Bot.), any grass of the genus Panicum. [1913 Webster]WordNet (r) 3.0 (2006):
panic grass n 1: any grass of the genus Panicum; grown for grain and fodder