Sunday, January 23, 2011

Cryptostylis subulata

Native ground orchids can be contrary beasts. Since I last blogged about Cryptostylis subulata (Large Tongue Orchid) growing in our garden four years ago, there have been none in flower here... till this week:

Cryptostylis subulata
Cryptostylis subulata

This specimen is growing on the edge of a sandstone platform, the flowers hanging down over the cave beneath.

There is much that is remarkable about C. subulata. As with the other species of the genus endemic to Australia, it is exclusively pollinated by the male ichneumon wasp Lissopimpla excelsa (the dupe wasp). The orchid flower mimics a female wasp, not only through its appearance, but also by exuding a chemical counterfeit copying the pheromone of the female wasp. The male tries to mate with the flower--even to the point of ejaculation--and in doing so, transfers pollen.

This sexual deception is an extraordinary example of an exploitative symbiosis. Many plants engage in deception to trick pollinators into transferring gametes for them, and it is particularly common among orchids. There are cases of orchids emulating brood sites, food, and in at least one curious case, a marauding bee. Real bees will attack and brush against the flowers of Oncidium hyphaematicum as they wobble in the breeze, the pollen adhering to their bodies for transport to the next orchid.

Orchids also have very specific mutualistic relationships with fungi. Their seeds are minute and lack endosperm--the portion of the seed that provides food for the growing plant embryo. They are entirely dependent on fungi for energy at this stage, and later, form crucial relationships with mycorrhizal fungi for nutrients. The relationship between the evolution of pollinator deception, fungal symbionts and orchid diversity is an area of research rich with promise.


A. C. Gaskett, C. G. Winnick, M. E. Herberstein (2008). "Orchid Sexual Deceit Provokes Ejaculation". The American Naturalist 171 (6)

A. C. Gaskett, M. E. Herberstein (2010). "Colour mimicry and sexual deception by Tongue orchids (Cryptostylis)". Naturwissenschaften 97: 97–102