The Collaborative International Dictionary of English v.0.48:

Zygophyte \Zy"go*phyte\, n. [Gr. zygo`n a yoke + fyto`n a
   plant.] (Bot.)
   Any plant of a proposed class or grand division (Zygophytes,
   Zygophyta, or Zygosporeae), in which reproduction consists in
   the union of two similar cells. Cf. Oophyte.
   [1913 Webster + CM]