With more than 12,000 species of endemic plant life, Madagascar is one of the most biologically diverse places on Earth, according to Conservation International. As much as 80 percent of Madagascar's flora is found nowhere else in the world, including 10 families and 260 genera of plants, making it second only to Australia in terms of biodiversity, states biologist C.R. Huxley in his book "Chorology, Taxonomy and Ecology of the Floras of Africa and Madagascar."
There are six species of baobab tree native to Madagascar, all members of the genus adansonia. Most frequently found in the dry deciduous forests of western Madagascar, baobab trees are perfectly adapted to living in the semi-arid conditions of that ecosystem. Growing to heights of 100 feet with a trunk diameter of up to 36 feet, baobabs are the largest trees in Madagascar, according to "Chorology, Taxonomy and Ecology of the Floras of Africa and Madagascar." The trees are easily recognizable by their swollen trunks, which can hold up to 32,000 gallons of water in anticipation of droughts characteristic of the region. Baobab trees are extensively used by the native people of Madagascar as a food source.
All six species of alluadia, or spiny plants, are an important component of Madagascar's spiny forest ecosystem. Although the plants can range in size from 6 to 60 feet in height, according to "Chorology, Taxonomy and Ecology of the Floras of Africa and Madagascar," all spiny plants have certain characteristics in common, such as succulent trunks with deciduous leaves interspersed by inch-long thorns. Differences among the species arise from their growth habit, which can range from a tall central trunk with spiny branches, as is found in alluaudia ascendens, dumosa, procera and montagnacii, to short, stocky trunked species such as alluaudia comosa and alluaudia humbertii.
With more than 1,000 species on the island, orchids comprise the largest plant family in Madagascar and, according to Philip Cribb, author of "Field Guide to the Orchids of Madagascar," more than 90 percent of those are found nowhere else on Earth. Habitat destruction is the main threat to orchids living in Madagascar, although orchid collectors harvesting from the wild are also an issue. Among the amazing variety of orchids native to Madagascar is eulophiella roempleriana, one of the largest and rarest orchids on the island. Found only in the tops of the common screwpine tree within a restricted range along the coast, the orchid has been collected to the point of extinction for its striking, magenta flowers.
Of the 170 species of palm found in Madagascar only five are found elsewhere in the world, according to researchers at Kew Gardens. Two of the rarest and most threatened species of palm in Madagascar are dypsis ambositrae, of which less than 20 specimens survive in the wild, and beccariophoenix madagascariensis, which is threatened by seed harvesters, who cut the trees down to better reach their seeds.
