Sarcolaenaceae a plant family found only in Madagascar, two species within it (Sarcolaena isaloensis and Schizolaena isaloensis) have only been found in Isalo NP. Lichens The lichens of Madagascar are poorly known, but over 500 species have been documented. Only about 20 species are found in the dry areas of the country. Several of these have been documented in the Isalo area, including the type specimen and only known location for the narrowly endemic Isalonactis madagascariensis. Vegetation Isalo is primarily within the dry deciduous forests ecoregion, an ecoregion in which natural vegetation has been reduced by almost 40% of its original extent. It also includes isolated forest patches classified as part of the subhumid forests ecoregion, an ecoregion that is home to numerous endemic species and has been given Critical/Endangered status because only small areas of native habitat remain and most of those are highly fragmented. Six main habitats have been described in Isalo NP. 1. Sclerophylous woodlands The sclerophyllous (hard-leafed, drought adapted) woodlands of Isalo are dominated by the endemic tree tapia (Uapaca bojeri). This is a woodland type that is restricted in distribution; found only in Madagascar's central highlands. Some of the largest intact areas of tapia woodlands are found in Isalo. These woodlands are adapted to regular burning and are characterized by a relatively open canopy dominated primarily by tapia, but other trees may include members of the family Euphorbiaceae or the endemic family Sarcolaenaceae. The main components of the shrub layer are made up of species from the families Asteraceae, Rubiaceae, and Leguminosae, but herbs and grasses form the main understory. Endemic Kalanchoe and Aloe species grow in this habitat. 2. Evergreen humid forest These forests are associated with moist habitats such as near streams or in the deep ravines. Native forests found in deep canyons have palm species (Ravenea and Dypsis species), Breonadia salicina, Weinmannia sp., Voacanga sp. and Dracaena sp. Some of these moist habitats however are now dominated by introduced species such as Melia azedarach, Mangifera indica or Eugenia sp. 3. Pandanus thickets Pandanus thickets, dominated by Pandanus pulcher occur associated with shallower valleys or small stream are where the forest is degraded and frequently burned. 4. Dry (xerophytic) vegetation This habitat is associated with dry rocky areas, including steep slopes and ridges. Although vegetation is sparse, a number of endemic species are found in these habitats, including Xerophyta sp., elephant's foot (Pachypodium