This paper reports on new dibenzofurans from Roccella species, the stuctural elucidation and synthesis of arthonin and hypothallin, new amino acid amino alcohol esters from lichens, crustinic acid, a new depside from Umbilicaria crustulosa, the HPLC of aromatic and aliphatic lichen substances, a new synthetic approach to dimethylorcinol and the chemistry of roccellic acid.