Rapa Nui is a volcanic island situated on the East Pacific rise by 27° 07' S and 109° 22' W making it the most isolated inhabited place in world. Formerly forested (Selling 1961; Flenley and King 1984; Flenley et aI, 1991; Orliac 2000), it now presents an open grassy landscape with several introduced plants such as banana, sweet potatoes and sugar cane. As to the sedge species nga 'atu (Schoenoplectus californicus subsp. tatora (Kunth) T. Koyama syn. Scirpus californicus) the status of this species appears more controversial.</p
