The deceiver

Fly orchid, Ophrys insectifera, Arnside Knott

I have only found one location for the fly orchid on the Knott, and there are fewer flowering spikes this year than last. There is another well-known site at Sandside, close to the road, and easily findable by the crushed grass all around the flowering plants left by botanical twitchers with cameras. This little site is clearly less well known.

Why the deceiver? The fly orchids, and other members of the genus Ophrys have an extraordinary strategy for pollination, known as pseudo-copulation. The fly orchid emits a scent which two species of solitary wasp find irresistible, a scent that must mimic the pheromone emitted as sexual attractants by the females. The wasps, Argogorytes mystaceus and A. fargei settle lengthwise on the flower's lip.

For what happens next, I will borrow the inimitable words of The Natural History of Pollination by Proctor, Yeo and Lack: "Often it remains on the flower for many minutes, every now and then restlessly changing its position before settling down again and performing movements which look like an abnormally vigorous and prolonged attempt at copulation. While it is on the flower, the wasp seems quite oblivious of the observer's presence."

It has to be said that the coloration of the flower is not a good match for the banded yellow of the wasp, but the shape and size is, and as the photograph shows, two of the flower petals are modified to look like antennae. While engaged in amorous activity, the male wasp's head is thrust into the hooded structure at the top of the flower lip. Here there are two sacs of pollen (visible in the shot) that become stuck to the wasp's head. When he is finished, yet with libido still intact, he visits another flower, repeats the same activity and the so-called pollinia stuck to his head are deposited on the stigma of the new flower. The pollen sacs contains thousands of pollen grains that mean that one act of pseudo-copulatory pollination can produce a multitude of seeds.

This account draws much on the description in Proctor et al, since alas, I have not seen it with my own eyes, but I solemnly promise to blip it when I do. And Dr Proctor is for me one of the great botanist heroes, a scientist and polymath of unparalleled knowledge across many disciplines. He has only recently published (at an age that must be close to 90) his third volume in the New Naturalist series, this one on the Vegetation of Britain. He is also a fellow of Royal Photographic Society, and his books are beautifully illustrated by his photographs. I owe him a debt personally too: he was the external examiner for my Ph.D., and though I struggled to understand some of his questions, never mind answer them, he was kind enough to pass me. He certainly would have seen through any deception.