Abstract Some new constituents were discovered in a very unusual spanish lavender: Lavendula luisieri (Rozeira) Riv. Mart. The essential oil of L. luisieri, which is produced on an industrial scale, was analyzed by a combination of GC and GC/MS. Many components identified were irregular monoterpenoids, with a cyclopentanic structures unique in the plant kingdom, like Î±-necrodyl acetate (20â25% of the oil) or Î±-necrodol. The new structures identified were: 3,4,4-trimethyl-2-cyclohexen-1-one, 3,4,4-trimethyl-5-hexen-2-one, 2,3,4,5-tetramethyl-2-cyclopenten-1-one, 2,3,5,5-tetramethyl-4-methylene-2-cyclopenten-1-one, 1,1,2,3-tetramethyl-4-hydroxymethyl-2-cyclopentene, 2,4,5,5-tetramethyl-cyclopentadien-1,3-carboxylic acid and selina-4,7(11)-diene. A monoterpene whose exact structure remains unknown, is present in the oil at a level of (2â4%). Other main compounds were 1,8-cineole and lavandulyl acetate.