India - an orchid paradise, if you know where to look...
André Schuiteman, Research Leader in the Identification and Naming Department at Kew, explains why India is rich in orchid species...but why they are not always easy to find.
Setting the scene
India is rightly called a subcontinent. In fact, until about 40 million years ago it was a true continent. Geologically, India was part of the ancient supercontinent Gondwanaland, and then became a dislodged fragment that drifted northwards until it collided with Laurasia. This collision caused the contact zone to crumple, and as a result the Himalaya were formed.
'What has this got to do with orchids?', you may ask. Well, if you want to know where India's orchids come from, and why they are found where they are today, then a big part of the explanation lies in the geological history of India.
An 'orchid ark'
Orchids are an old plant family, thought to have been around for some 110 million years. Vegetarian dinosaurs may have nibbled on orchid leaves. It is likely that orchids already thrived in India when it was drifting across the Tethys Ocean, well before it hit Laurasia. Perhaps those orchids, growing in India when it was still a real continent, are the ancestors of most of the orchids that occur in tropical Asia today. India may have been a kind of 'orchid ark', carrying orchids from the south, where the orchid family is believed to have originated, to the north.
Age of discovery
Many botanists have described Indian orchids during the last few centuries. Linnaeus, in 1753, already knew a handful of them, but the great majority were discovered during the 19th century. This age of discovery culminated in the publication of the orchid chapters in the Flora of British India, published in 1890 and 1891 by Joseph Hooker, then director of the Royal Botanic Gardens, Kew. Another landmark publication of that age was The Orchids of the Sikkim-Himalaya, published in 1898 by George King and Robert Pantling, who worked at the Royal Botanic Gardens of Calcutta. King and Pantling described so many new species that the Flora of British India became almost obsolete less than ten years after its publication.
New Indian orchids still being discovered
Numerous books and other publications on Indian orchids have followed, and new orchid species are still being described from India, not just once in a while, but on average several times each year. At present about 1,250 species have been recorded. An update of Hooker's work is sorely needed, for although there are many fine books on the orchids of specific parts of India (mostly at the state level), a modern comprehensive work is lacking.
Which states have the most orchids?
I am currently working with colleagues from the subcontinent to prepare an up-to-date list of all the orchids of India. This is part of a general checklist of the plants of India coordinated by Missouri Botanical Gardens. The simple map shown here is based on this list of orchids; it indicates (by state) how the orchid diversity of India is distributed geographically. The 'hotspots', the richest areas, are indicated in red. We see at once an interesting pattern. All the western states, like Rajasthan and Jammu & Kashmir, are quite poor in orchid species, with fewer than 20 species in each state. You shouldn't go there if you want to see wild orchids. In contrast, the eastern states, like Arunachal Pradesh, Assam, Meghalaya and Sikkim, are species-rich, with close to 600 species in Arunachal Pradesh.
Mountains are a great place to look
It turns out that the poorest parts of India, in terms of orchid species, are also the driest, while the richest are also the wettest. But high rainfall is strongly correlated with the presence of mountain ranges. Orchid richness in states like Karnataka and Maharashtra is mainly confined to the mountain ranges along the coast. Of course, there is no more prominent mountain range than the Himalaya, and it is almost certain that India would have had far fewer orchid species if the Himalaya had not arisen over the last 40 million years.
Orchids in peril
Sadly, deforestation and indiscriminate collecting of wild orchids for horticulture and traditional medicine have caused numerous orchids to become endangered species in India. Many, including most of the slipper orchids (Cypripedium and Paphiopedilum), are close to extinction. If you want to see those in the wild, you really have to know where to look. There may well be more plants of Paphiopedilum druryi in cultivation than there remain in the wild. Other species, less glamorous, may not even be in cultivation anywhere. They may soon be lost forever, ending a journey that began millions of years ago, when India left Gondwanaland.