The variability of pyrenes in the paleotropical genus Chassalia is described and illustrated. Four different pyrene types can be distinguished: (I)open pyrenes, characterized by an open ventral excavation, (2) closed pyrenes, with a ventral excavation that is largely covered by the endocarp. (3) flat pyrenes, in which the ventral excavation is (almost) completely lacking, and (4) grooved pyrenes with two ventral grooves separated by a median crest instead of a ventral excavation. A continuous morphological series can be established to connect these types. The pyrenes of Chassalia are compared with those of Geophila and Hymenocoleus and confirm the close relationship of the three genera, which was suggested by macromolecular data.