One beautiful orchid may just be. Two set you thinking. The orchid house of Lloyd Botanical Garden in Darjeeling was filled with flowers of two species of Venus slippers, the genus Paphiodedilum. I showed photos of P. insigne some time ago. You can see here the similar shaped flowers of the Paphiopedilum villosum that grew cheek by jowl with it in the greenhouse. I was startled to find later that this genus has 70 to 80 known species. The genus seems to have originated between 5 and 7 million years ago in a geographical region called the Sundaland, which is the Indonesian and Philippine islands and the Malay peninsula. The present range of these slipper orchids extends southwards to New Guinea, and northwards to Southern China and eastern India.
The late Miocene was a time when the earth’s climate was changing rapidly. With a lot of the ocean’s waters locked into ice, the Sunda islands could have been joined by land bridges, allowing the earliest of these orchids to slip across the land. The great flowering, so to say, of species in this genus began about 5 million years ago, in the early Pliocene, when the waters rose again, splitting the land into islands. By then the increasing height of the Himalayas and the closing of the Tethys seaway had changed the global climate (incidentally causing large evolutionary changes among our ancestors) and the slippers evolved into humidity-loving species.
The climate and conditions in the core areas of Venus slipper diversity do not seem so different from each other; after all they have similar temperatures and humidity. But the many of these orchids have found extremely specialized niches in the ecology: some growing only on cliffs near the sea, others, like these Assamese species, in very humid rainforests high in mountains.
Interestingly, the actual process of evolution in these plants has also been studied. The genome of these orchids seems to be highly fragile, and repair mechanisms have created the variation needed for speciation. The evolution of these slippers is still ongoing in the wild. This could also explain why the slipper orchids are popular among orchid enthusiasts who love to create hybrids. That would be an interestingly complete story, if a geneticist actually bothers to study these hybrid varieties of slippers.