In prehistoric times montane forest occupied one-third of the territory of present-day Rwanda. Naturally occurring vegetation is now mostly restricted to the three national parks, with terraced agriculture dominating the rest of the country. Nyungwe, the largest remaining tract of forest, contains 200 species of tree as well as orchids and begonias. Vegetation in the Volcanoes National Park is mostly bamboo and moorland, with small areas of forest. By contrast, Akagera has a savanna ecosystem in which acacia dominates the flora. There are several rare or endangered plant species in Akagera, including ''Markhamia lutea'' and ''Eulophia guineensis''.