The Collaborative International Dictionary of English v.0.48:

Zizania \Zi*za"ni*a\, n. [NL., from L. zizanium darnel, cockle,
   Gr. ?.] (Bot.)
   A genus of grasses including Indian rice. See Indian rice,
   under Rice.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Zizania
    n 1: wild rice [syn: Zizania, genus Zizania]