In the frond waxes of Osmunda regalis four homologous series of previously unknown compounds were detected. In order to assign their structures various derivatives were prepared and analyzed by GC-MS. The wax components were identified as C-28 to C-32 alkanediols, C-26 to C-36 ketoalcohols, C-28 to C-36 ketoaldehydes and long-chain fatty acid esters of C-28 to C-36 ketoalcohols. All fractions showed strong prevalence of even numbered homologues with a maximum for C-30. Isomer distributions were in all cases dominated by 1,9, 1,11-, 1,13- and 1,15-compounds, their relative abundances shifting towards the latter with increasing homologue chain length. A total of 77 (69 novel) compounds were identified, partially as minor components in unresolved isomer mixtures. (C) 1999 Elsevier Science Ltd. All rights reserved.