Summary Trilete spores of land-plant type have been recovered from probable late Llandovery to early Ludlow sediments in several widespread parts of Ireland, and they have proved to be stratigraphically useful in otherwise unfossiliferous outcrops. In many cases, spores have been found in offshore marine sediments of turbidite facies in which they are accompanied by only minor quantities of marine palynomorphs (acritarchs, chitinozoa). Possible explanations for this unexpected association are considered in the light of what is known of Irish Silurian palaeogeography; they include reworking of nearshore shelf assemblages by turbidity currents and contour currents, and transport of land-derived spores by wind and surface-water currents. The possibility that the spore-bearing plants were pelagic is also considered.