Abstract

The archipelago of Juan Fernández (Robinson Crusoe) is located to 670 km. west of Valparaiso, in the Pacific Ocean. It is formed by 3 islands, all of volcanic origin: Masatierra (Robinson Crusoe), Masafuera (Alexander Selkirk) and Santa Clara. Johow and Skottsberg have made the most complete inventories of the flora of this archipelago. The most recent study is the one of Danton & Perrier. The documented flora include 423 species of vascular plants, 55 Pteridophyta, 289 Dicotyledoneae and 79 Monocotyledoneae. Of the total number of species, 31.2% are endemic, 18.7% native and 50.1% introduced. The Poaceae family represents 11% of the total flora of the islands and displays 53 species included in 32 genera, of which 9,4% are endemic, 9,4% native and 81,2% alien. In this work a key for the genera and a description of the species are given. Information in relationship to the iconography, distribution, ecology, conservation and examined material is presented. These results are compared and discussed with the ones of Danton & Perrier (2006).