The tiny tropical island of Mauritius in the south-west Indian Ocean has evolved a unique flora; almost one-third of its ca. 900 indigenous plant species are endemic. However, the survival of most of these unique plants, including all the endemic fern species, is seriously threatened by habitat destruction. Today, 99% of the native forest has been removed and replaced largely by sugar cane plantations. The largest remnant of native forest is now contained within the Black River Gorges National Park but, although protected from further destruction by man, it is rapidly being suffocated and replaced by a few highly invasive introduced plant species. The two most aggressive aliens are Chinese guava (actually from Brazil) and privet from Sri Lanka. Although only introduced early this century these two species now dominate many parts of the remaining forest and form thickets so dense that indigenous plants cannot regenerate. Ferns appear to be particularly vulnerable and of the 250 taxa that have been recorded from Mauritius, 48 have not been seen in recent years and are presumed extinct. Despite this, there are still many interesting taxa among those that survive and at least 17 are endemic. In 1995, the Royal Botanic Garden Edinburgh (RBGE), in collaboration with the National Parks and Conservation Service in Mauritius, launched a joint project to ensure the continued survival of these and other endangered fern species. In addition to field surveys and taxonomic investigations, a large fern propagation unit is being built near the Botanical Garden in Curepipe and scientific and horticultural staff from RBGE have been providing advice and training to local biologists on all issues relating to the design and implementation of a long-term pteridophyte conservation programme. The initial phase of this programme is funded by the UK Government through its Darwin Initiative for the Survival of Species Scheme.

Key words: Conservation, Darwin Initiative, Fern, Invasive Species, Mauritius, Pteridophyte