(Editor's Note: This article was originally published on April 4, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions.)
The archipelago lays in the South-West Indian Ocean, between latitude 19°45' and 20°51' South and longitude 57°18' and 63°25' East, slightly above the Capricorn tropic, 700 km east of Madagascar and 2000km east of Africa. The climate is therefore tropical, tempered by altitude on Reunion, with basically two seasons ; the cool one with temperatures around 20-22°C (68-71°F) and a warm one with temperatures around 26-28°C (78-82°F.), which is also the cyclones season...Rains are unevenly distributed, the eastern coast of Reunion having a world record with 2735 mm in three days in 1987 while the western part has very dry parts with Euphorbias and other succulents growing. All three islands have the same geological background, formed by emerging volcanoes, the only still active one being on Reunion, the Piton de la Fournaise, which spits lava in the Ocean every once in a while. Mauritius is the elder of the gang, with eight million years while Reunion is only three million years old and infant Rodrigue just one and a half. The most evident effect of this age difference is that Mauritius is rather flat and eroded while Reunion is still very mountainous and steep, the highest point at Piton des Neiges is 3070 m (6210 feet) high.
Now, the historic part ; Pedro de Mascarenhas, a Portuguese admiral is the one who gave its name to the archipelago though Reunion was discovered in 1507 by Fernandez Pereira, another Portuguese seaman. French people started to settle in 1665, and coffee as well as sugarcane crops which began in the 18th century required many slaves from India, Africa and Madagascar. It is more or less what happened in Mauritius, so those islands have remained virgin paradise void of men for millions of years...But the islands were first discovered by Arab sailors during the tenth century though they only used them for water supply and hunting.
The flora of the Mascareignes has a quite high endemic rate (endemic means that the concerned species, either plant or animal, developed only in the concerned place and will not be found anywhere else unless it has been exported). 526 species endemic to the archipelago have been described so far. This high endemism is the result of geographical isolation and long-time evolving. Seeds and plants parts started to be washed ashore as soon as the lava was cold, coming on sea currents from Africa, Madagascar and Indo-Pacific area, then slowly evolving. Other seeds or spores were brought by cyclones and birds. Another characteristic of the local flora is the heterophily which means that a plant in its young stage will have very different leaves in terms of shape, colour and size than the same plant once adult. So what looks like two different plants might be the same species at different ages...Reunion has a much richer flora than Mauritius because of the mountains which make part of the inner island unreachable and certainly impossible to use for crops, the elevation giving also raise to many micro-climates and ecological niches. Endemic plants are found amongst trees ; Mimusops maxima (Sapotaceae family), Agauria salicifolia (Ericaceae), Aphloia theaeformis (Flacourtiaceae), amongst epiphytes (plants which grow on another one though not being parasitic) such as orchids like Bulbophyllum sp., Angraecum squamatum or ferns like Blechnum attenuatum, Antrophyum boryanum, Cyathea borbonica (one of several tree ferns), amongst vines ; Hugonia serrata (Linaceae), Danais fragrans (Rubiaceae) etc...
Of course this endemic flora have greatly suffered once men began to settle, logging trees for building ships, houses, cutting down edible palm trees, burning the forest in order to grow food. Another hard hit was the introduction of foreign plants, some becoming such invasive species that they do colonize whole areas like Hedychium gardnerianum, Psidium cattleyanum, Syzygium jambos, Lantana camara and so on. Local botanical institutions now work on a preservation schedule, growing endangered species and reintroducing them back in the wild. Many endemics can be seen while hiking around the island, a favourite activity here.
Though those islands are quite small (Reunion is 2512 square km, Mauritius 1865 and Rodrigue only 119) they do have a lot to offer for the nature lover though you have to appreciate plants are animals are rather scarce and limited mostly to birds and insects.