Three genera of the Proteaceae belonging to the tribe Grevilleeae occur in the Guianas and Brazil: Roupala, Panopsis, and Euplassa. The microscopical wood structure of one of these genera, Euplassa, has not been described before. Anatomically it proves to be nearly identical with Panopsis which it also resembles in general properties. Roupala differs in several respects. Within the genera differences are not fundamental and chiefly a matter of numbers and dimensions. A key to the genera is given. The relation of these three genera with the two other members of the tribe in South America, Orites and Gevuina, is discussed.