trilete

Trilete is a term used in palynology and paleobotany to describe spores or pollen grains that bear a tri-radiate mark on their outer wall (exine). This characteristic scar takes the form of three radiating lines or lobes that meet at a central point, producing a Y-shaped or three-armed motif on the surface of the grain.

The trilete mark forms when a spore is produced as part of a tetrad during meiosis. As the four resulting spores separate, three germination lines coalesce at the center, leaving a three-armed scar that delineates the former tetrad boundary. The presence of a trilete mark indicates a spore developed from a tetrad and is commonly found in many fossil spores and pollen from Paleozoic and later periods. The morphology and distribution of trilete spores are used in biostratigraphy and paleoenvironmental reconstructions, aiding correlations of sedimentary sequences.

Under microscopy, the trilete mark appears as a central locus with three extending arms that can be observed with light or scanning electron microscopy. The term derives from Latin tri- “three” and latus “side,” reflecting the three-armed nature of the scar. Trilete spores are a diagnostic feature in the study of ancient terrestrial vegetation and are frequently cited in discussions of palynological assemblages. See also palynology, spores, pollen, biostratigraphy.