Which is in the grass family, Pachypodium or Arrhenatherum?
Pachypodium Pachypodium is a genus of succulent spine-bearing trees and shrubs, native to Madagascar and Africa. It belongs to the dogbane family, Apocynaceae. "Pachypodium" comes from a Latin form from Greek "pachus" (thick) and "podion" (foot) (or Gk podos, root form of pous, foot), hence meaning "thick-footed".
Rhipidocladum Rhipidocladum is a genus of New World woody bamboo in the grass family). It found in Mesoamerica, Trinidad, and South America. The genus is characterized by 1) erect, non-pseudopetiolate culm leaves, 2) numerous branchlets arising in an apsidate (fan-like) array, and 3) fruits being true caryopses. The name is derived from the Greek "rhipid" meaning "fanlike" and "clad" meaning "branch".