Southern and Southwestern Madagascan BioProvince
This BioProvince (as defined by Armen Takhtajan) comprises the south and southwestern coastal zones of Madagascar. Its northern border extends to the Mangoky River on the west coast and to the western slopes of the Anosyennes Mountains. The area lies in the extreme rain shadow of the eastern mountains. Consequently it has a dry season that can last up to 11 months. This lack of water is further exacerbated by the highly porous nature of the bedrock, which is composed of limestone and sandstone. Most of the plant life therefore shows extreme adaptation to draught with many species having xeric adaptions similar to New World cacti such as small leaves and spines but many are woody rather than succulent. Others have extensive root systems with massive tubers or enlarged trunks and branches. This extreme adaptation no doubt accounts for much of the endemism in this area. In fact, it has a higher level of endemism than any other part of the Madagascar, with some 48% of genera and 95% of species endemic, although recent studies suggest that only about 53% of species are strictly endemic to this biozone. It also has a near endemic family (Didiereaceae). The primary plant communities mainly comprise the now famous spiny forest.
The following accounts for this BioProvince have been written or will be written with particular reference to endemic and locally important species. Accounts available are displayed in green or yellow. Those displayed in red are either in the pipeline or awaiting expert contributions.
|Endemic Vascular Plant Flora|