How Many Orchid Species?

Abstract

In the 1980s, careful estimates of the size of the Orchidaceae clustered around 19,000. A new provisional checklist suggests 24,500 species of orchids, approaching the "improbable maximum of 25,000," as seen by John Atwood. Recent lists from Mesoamerica agree closely with the 20% increase indicated by the provisional list. Will the next two decades bring in another 5000 new orchid species? The answer is unknown, but there are clearly many new species to be found in tropical America. Showy, new, large-flowered species are relatively few, rather the vast majority of species are small-flowered, if not microscopic. Ephemeral flowers, such as Sobralia, Palmorchis, and the Triphoreae, have special problems associated with their identification, for which most field-collected herbarium specimens are nearly useless. In practice, most large-flowered orchids are poorly represented by herbarium specimens, and even many small-flowered species are scarce in the herbaria. Only abundant and widespread species, such as Epidendrum radicans or Habenaria monorrhiza, are really well represented in the herbaria. In Central America, it is interesting to compare Costa Rica, with its tradition of resident naturalists, with Panama, where resident naturalists have been very few. Now the Panamanian orchid flora is rapidly catching up with Costa Rica, but both countries have significant areas that are poorly sampled. Much work remains to be completed, but when someone looks for them, many more new species will appear.