Orchids of Reunion island
Reunion island is a rather tiny dot on the South-Western part of the Indian Ocean (see this article for more information) ) and only makes some 70km long and 50km wide but it is host to an amazing diversity of microclimates due to the two opposite coasts--the dry West coast and the rainy East coast which, added to the very chaotic relief (a still active volcano at 2631m high and an inactive one at 3069m), produces some 200 registered micro-climates! Such a diversity has of course given birth to a high diversity within the local plant kingdom and explain why on such a tiny dot 120 species representing some 30 different genera of orchids can be found in the wild. Most of those can be related to orchid species growing in the area like Madagascar of the Comoro archipelago but about twenty percent cannot be related and are thus endemics to Reunion. Of course many species have disappeared since humans settled on the island and cleared land all around the island, first for family crops and later for industrial crops such as coffee and sugar cane. But fortunately the island's terrain is very steep and people did not clear the forest inland, so we can still enjoy large parts of primary forests. Another feature which has greatly helped preserving our local orchids is the fact that many display rather small and poorly coloured flowers, an important deterrent to human predators!
As is the case for most tropical orchids (as opposed to orchids in temperate or Mediterranean areas), the majority are epiphytic which means that they grow on other plants such as trees though not being parasitic in any way. There are of course a few terrestrial species so the orchid amateur needs a very flexible neck, checking both the ground and upper branches when strolling in the wild. Some are lithophytic which means that they grow on stones.
As we do not have much time, we will not go hiking and meet all 120 different species, but we will just hop here and there and admire a few of them. Keep in mind that most wild orchids here bloom during the wet or cyclonic season, which means a rather hot and humid time of the year--light clothes and an efficient hat are needed. As said before, some plants will happily grow on the forest floor and are easily accessible, while most will require some tree climbing to be reached. A few of the lithophytic species may require the use of ropes and harnesses, as they enjoy growing on cliffs where there will be no branches to hold on to!
Let us then start with a rather tricky one so as to sharpen your orchid hunter's eyesight; Aeranthes arachnites displays small green flowers so you have to pay some attention not to miss them. The Aeranthes genus comprises some 40 species, mostly from Madagascar and they produce long flexible petioles at the end of which the flowers seem to float in the air (thus the name; ‘aer' means air and ‘anthes' flower). It usually grows in wet forests at low altitude though it can be found as high up as 600m.
Subtly colored, but easier to spot with its white flowers is the endemic Angraecum bracteosum. The Angraecum genus is quite large, with some 130 species described in Madagascar and about 70 for Africa, the Comoros, Seychelles and Mascareigne archipelagos out of which Reunion has some 30 species and more get discovered every once in a while. A. bracteosum is often seen in wet and shady forests, it can reach a nice size with leaves up to 50cm long.
Benthamia latifolia is another species with discreet greenish flowers but it produces a large flower spikes with a lot of them. A terrestrial species, it also enjoys humid forests at medium altitude, between 800 and 1500m high and will happily grow out of a thick mattress of mosses.
Now a very large genus, the Bulbophyllum hosts between 1500 and 2000 species according to different authors. It also has a very large geographical repartition area as it grows in Asia, Australia, Oceania, Africa, Latin America. Reunion has about 20 different species, some very common which literally covers trunks and branches in rain forests of the South. B. occultum pictured here got its species name from the fact that the tiny flowers remain hidden by the large green bracts.
Ah, this one will please more folks, I can tell right away. Although it has been classified for a long time as Bulbophyllum and very probably is a local evolution of the African-Malagasy B. longiflorum, this delicious one is now called Cirrhopetalum umbellatum. It enjoys sun and will therefore be found at the very top of large trees or even growing on rocks in a clearing or hanging on a cliff (where the pictures displayed here have been taken--just think to what lengths I go for your pleasure! Interestingly enough it blooms with different colours, from bright yellow to pale yellow with red parts and spotted red, always a stunning encounter.
No, this is not an alien from another galaxy though it looks weird, Cryptopus elatus has a unique shape and is a quite rare species. It has a special way of growing as it clings to trees but with long-reaching roots which keeps the plant a long way from its prop, this feature means that when a cyclone hits the plant can easily be torn from the tree but it will grow back even if it has to take an arched shape.
Yes, some colour now, the terrestrial and common Cynorkis purpurascens will produce flowers from pale mauve to bright purple. It is an often seen one along trails mostly at some altitude in rainy areas. It grows a unique wide leaf.
The Jumellea genus hosts some 10 species on Reunion. The most famous one is J. fragrans locally known as ‘faham' and used to make a delicately perfumed drink when soaked in rum. But we will not indulge in such things and introduce here only J. recta which flower is quite similar but which lacks this special perfume. This species is able to grow on rocks in full sun and will then produce short leathery leaves.
We will end this short promenade with a very rare species which I encountered only once here but also spotted in a forest in Madagascar. Oeonia rosea has a very delicate appearance with wiry stems and small leaves.
I hope this short insight into the stunning word of orchids was as much a pleasure to read as it was a pleasure to write. The species here are far from what are commonly sold in nurseries, but they seem more precious to me!
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