In a screening of 43 accessions of predominantly Australian sundew species (Drosera), naphthoquinones were detected convincingly for the first time in D. section Lasiocephala (D. petiolaris group, or 'wooly sundews'), where these metabolites remain restricted to a minority of four closely related species. Great chemical similarity across the large geographic range confirms a close phylogenetic affinity between taxa of the D. peltata species group (of D. section Ergaleium, from tropical and Eastern Asia to New Zealand). Drosera barrettiorum (D. section Arachnopus) is chemically confirmed as a close relative of D. hartmeyerorum. The recently described species D. margaritacea in the same section is chemically different from the morphologically close D. finlaysoniana. Quinone data for African and South American sundews (D. sections Drosera, Ptycnostigma and Brasilianae) shed further light on the affinities between these taxonomically challenging plants.