More than 80 percent of Madagascar’s 14,883 plant species are found nowhere else in the world, including five plant families.There are several endemic families including the Asteropeiaceae, Sarcolaenaceae and Sphaerosepalaceae. The humid eastern part of the island was formerly covered in rainforest with many palms, ferns and bamboo, although much of this forest has been reduced by human activity. The west has areas of dry deciduous forest with many lianas and with tamarind and baobabs among the dominant trees. Subhumid forest once covered much of the central plateau but grassland is now the dominant vegetation type there. The family Didiereaceae, composed of four genera and 11 species, is limited to the spiny forests of southwestern Madagascar.
Four-fifths of the world’s Pachypodium species are endemic to the island.Three-fourths of Madagascar’s 860 orchid species are found here alone, as are six of the world’s eight baobab species. The island is home to around 170 palm species, three times as many as on all of mainland Africa; 165 of them are endemic.
Many native plant species are used as herbal remedies for a variety of afflictions. The drugs vinblastine and vincristine, used to treat Hodgkin’s disease, leukemia and other cancers, were derived from the Madagascar periwinkle.
The traveler’s palm, known locally as ravinala and endemic to the eastern rain forests, is highly iconic of Madagascar and is featured in the national emblem as well as the Air Madagascar logo.