ABSTRACTSixteen characteristic aromatic lichen products were identified in alga-free fungal cultures derived from single-spore isolates of four chemotypes of theRamalina siliquosaspecies complex. The chemistries of many cultures are more complex than those of natural thalli. The compounds identified include the majorβ-orcinol depsidones that characterize the chemotypes as well as biogenetically reasonable precursors not yet proved in natural thalli. Single-spore progeny from natural thalli can be assigned to chemotype without being lichenized with an alga. This result simplifies the use of secondary-product chemistry as a genetic marker to assess the limits of gene flow between chemotypes in natural populations.