Thursday, 18 July 2013

Orchids offer a taste of the exotic

A thriving colony of bee orchids, discovered by a friend within the last fortnight, has brought a taste of the exotic to my local patch. The bee orchid is one of our most showy orchids, its elaborately patterned flowers used to attract the bees that act as pollinators. This is one of four Ophryus orchids to be found in Britain, the others being the fly orchid, early spider orchid and late spider orchid. Despite their name, the spider orchids also have flowers shaped to attract bees. Interestingly, these flowers do not offer the bees any reward since they do not contain nectar. Instead, male bees are fooled into ‘mating’ with the flower through a series of visual, tactile and olfactory deceits. In addition to looking and feeling like a female bee, the flower releases a scent which mimics the pheromones produced by a virgin female. The quantities of these chemicals produced may even be such that the flower becomes more attractive to a male bee than a virgin female.

Somewhat surprisingly, the bee orchid has largely abandoned this method of pollination and is now self-pollinated – the three related species continue to use bees. Quite why this has happened is unclear, although it is a fairly recent phenomenon and does not seem to have hindered the success of the bee orchid, which is found across most of England. Bee orchid shows a preference for areas of disturbed ground, presumably where it can cope with the competition, and old grassland or scrub sites on chalky or sandy soils can support sizeable colonies. These days it is the only one of the four species likely to be encountered in Norfolk, occasionally even turning up in gardens.

The wider group of orchids to which these species belong contains in excess of 240 species, making this the largest of the European orchid groups. Although members of the group can be found across Europe, reaching as far north as Scandinavia, the greatest diversity is to be found around the Mediterranean. This underlines the complex relationships that must exist with particular pollinators, the orchids diversifying to exploit the range of potential pollinators present. We may be some way from the Mediterranean but at least we have the bee orchid to bring a taste of the exotic.

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