The authors performed a preliminary survey of Festuca rubra L. s.l. in the outer dunes of the West- Frisian island of Terschelling. Starting-point was the question which dune-form of this grass — Festuca juncifolia St. Amans or Festuca rubra subvar. arenaria (Osb.) Hack. — was growing there. In the transsects I and II (fig. 1) on the northern coast of the island a number of plants of Festuca were investigated. Six characteristics were analysed; the most important was the manner in which fibres (sclerenchyma) in the leaf-blades occur (fig. 2). It appears that especially Festuca rubra subvar. arenaria is common in the outer dunes of Terschelling. A continuous layer of fibres — characteristic of juncifolia — was not found in the plants studied. This result is remarkable, because juncifolia too should be rather common in the Dutch islands according to the literature.