Saturday 23 June 2012: Bee orchid...more mimicry
I've had a wonderful day today at a Botanical Society of the British Isles field meeting at Grimsthorpe Park in Lincolnshire, botanising in some very well managed species-rich limestone grassland. There was a good turnout, comprising a wide mix of ages and levels of experience. One of the particular attractions of the site was opportunity to view a population of early gentian Gentianella anglica, a rare endemic species which I'd never seen before. But perhaps the two most exciting and unexpected finds were henbane Hyoscyamus niger (again!) and a good colony of night-flowering catchfly Silene noctiflora, a rare and declining arable species of light soils.
I was too involved in botanising and chatting to take many photographs, but I couldn't resist this beautiful bee orchid Ophrys apifera, in the peak of perfection. This species is an attractive orchid with several small flowers, each of which has a lip resembling a bee, and three large, pink, petal-like outer sepals; the two other inner sepals look like antennae. The whole flower thus mimics an insect feeding on a flower. In biology, the term 'mimicry' refers to cases where natural selection has favoured a resemblance between individuals of different species, and there are numerous examples of orchid flowers which resemble their insect pollinators.
In other Ophrys species in the Mediterranean region, for example, male bees or wasps try to copulate with the lip of the flowers, which look and smell like the females of their own species. However, in Britain and generally elsewhere, the bee orchid, is self-pollinated and the pollinia, which hang on a thread, are blown against the receptive surface of the stigma.
The minute seeds are produced in thousands and can blow several kilometres, so bee orchids can appear unexpectedly, especially in exposed ground such as on road cuttings, quarries and other industrial sites, often on chalk or limestone soil.
PS I'm afraid that yesterday will be the first permanent gap in my journal. I only took three photographs and accidentally deleted them while dog-walking this morning!