Distribution of triterpenoids and related compounds was examined for six species of Gramineous plants, with special reference to the chemotaxonomical point of view. The triterpenoids thus identified are shown in Table I. Arborinol methyl ether (Vd), a new triterpene methyl ether, was isolated from the culms and leaves of Imperata cylindrica BEAUV. var. koenigii, DURAND et SCHINZ and identified with the synthetic specimen.