<P> The Caribbean is a focal area for many hurricanes within the Western Hemisphere . A series of low pressure systems develop off the West coast of Africa and make their way across the Atlantic Ocean . While most of these systems do not become tropical storms, some do . The tropical storms can develop into Atlantic hurricanes, often in the low pressure areas of the eastern Caribbean . The Caribbean hurricane season as a whole lasts from June through November, with the majority of hurricanes occurring during August and September . On average around 9 tropical storms form each year, with 5 reaching hurricane strength . According to the National Hurricane Center 385 hurricanes occurred in the Caribbean between 1494 and 1900 . </P> <P> Every year hurricanes represent a potential threat to the islands of the Caribbean, due to the extremely destructive nature of these powerful weather systems . Coral reefs can easily be damaged by violent wave action, and can be destroyed when a hurricane dumps sand or mud onto a reef . When this happens, the coral organisms are smothered and the reef dies and ultimately breaks apart . </P> <P> The region has a high level of biodiversity and many species are endemic to the Caribbean . </P> <P> The vegetation of the region is mostly tropical but differences in topography, soil and climatic conditions increase species diversity . Where there are porous limestone terraced islands these are generally poor in nutrients . It is estimated that 13,000 species of plants grow in the Caribbean of which 6,500 are endemic . For example, guaiac wood (Guaiacum officinale), the flower of which is the national flower of Jamaica and the Bayahibe rose (Pereskia quisqueyana) which is the national flower of the Dominican Republic and the ceiba which is the national tree of both Puerto Rico and Guatemala . The mahogany is the national tree of the Dominican Republic and Belize . The caimito (Chrysophyllum cainito) grows throughout the Caribbean . In coastal zones there are coconut palms and in lagoons and estuaries are found thick areas of black mangrove and red mangrove (Rhizophora mangle). </P>

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