Which of these names is a genus of plant that consists of grass species:  Poa or Gymnocladus?
Gymnocladus Gymnocladus (Neo-Latin, from Greek γυμνὀς, "gymnos", naked + κλάδος, "klados", branch) is a small genus of leguminous trees. The common name coffeetree is used for this genus.
Achnatherum Achnatherum is a genus of plants which includes several species of needlegrass. Several needlegrass species have been switched between "Achnatherum" and genus "Stipa"; taxonomy between the two closely related genera is still uncertain.