British orchids
Orchids are spectacular, deceive insects for a living and develop amazingly complex bonds with fungi. Jon Dunn falls under their spell.
How these beautiful flowers are masters of deception
When we think of orchids our minds likely conjure images of jungles and humid cloudforests in faraway lands, festooned with improbably exotic blooms. And yes, many of the world’s estimated 25,000 species of orchid flourish in those sorts of surroundings. But here in the British Isles there are orchids every bit as beautiful, charismatic and highly evolved as their tropical counterparts. Indeed, some of our native orchids are probably rarer and more vulnerable than almost any other wildflower you’d care to name.
We have around 52 species (since orchid taxonomy is complex, the exact number is open to debate) and the more plentiful ones are all around us. You seldom have to travel far to enjoy common spotted or early purple orchids. Other often-abundant species include the southern and northern marsh, pyramidal and heath spotted orchids. Many a rough grassland, meadow, wood or well-maintained road verge will have at least one of these beautiful wildflowers.
Unbeknown to many, some orchids even thrive in urban surroundings. Glasgow may seem an unlikely location in which to look for orchids, yet it’s actually the easiest place in Britain to see broad-leaved helleborines. In late summer they happily flower in cracks at the sides of pavements. Their exuberant spread into the very centre of this city challenges our perception of orchids as being the rarefied aristocrats of the plant world. Bee orchids, too, turn up
beside busy roads; they have even sprouted on a verge near Gateshead’s giant Metro Centre.
That said, some of our native orchids do have very refined tastes and requirements if they’re to prosper. Many species have seeds that will only germinate and grow in the presence of specific fungi in the soil. This makes life much harder for conservationists attempting to save our most threatened species, by growing specimens to reintroduce into suitable habitat in the wild.
LADY LUCK
Botanists at Kew Gardens have learned how to bypass this fungal requirement for the germination of lady’s slipper orchid seeds, as featured in BBC Wildlife in October 2014. Just in the nick of time too, for by the 1980s our native population was down to a single plant growing in the wild. The rescue work has led to the successful reintroduction of hundreds of cultivated lady’s slipper orchids grown from wild seed, which now thrive at a number of the species’ former strongholds in northern England.
But another threatened orchid, the red helleborine, continues to defy all attempts to rear it in captivity. Found now at just two sites in the Cotswolds, it appears to be heading for local extinction – a decline not helped by the
OPHRYS ORCHIDS MIMIC THE SHAPE AND FORM OF INSECTS IN ORDER TO LURE POLLINATORS.
apparent absence in England of the precise species of bee that pollinates their counterparts in mainland Europe.
A close relationship between plant and pollinator is typical of a number of our orchids. One particular family, the Ophrys orchids, take this to the most dramatic of extremes – their flowers mimic the shape and form of insects in order to lure their pollinators to them. Fly orchids, despite their name, rely upon digger wasps for their pollination. Their flowers are slender and furry, with a shiny ‘speculum’ that gives the impression of wings on a resting insect’s back, as well as beady, glossy black ‘pseudo-eyes’ and petals that look just like insect antennae.
SCENT TRAP
More remarkable still, each flower emits a scent that mimics the pheromones released by a virgin female wasp – no wonder male wasps are irresistibly drawn to them and compelled to attempt to mate with the flowers, a behaviour known as pseudocopulation. While the act itself may be unrewarding for the wasp, it’s essential for the orchids. Unwittingly, the insects carry pollen from one orchid close encounter to another.
Britain’s bee orchids have dispensed altogether with the need for an insect pollinator. While an intervening insect is welcome for sharing a little genetic diversity between plants, these orchids invariably pollinate themselves within a matter of hours, relying only on a faint gust of wind to blow their sticky pollen onto their receptive stigma. Other orchids ap appear to deploy chemical warfare to ensure their pollin pollination. For example, the nectar of broadleaved helleborine helleborines contains a number of narcotic alkaloids. Their nectar is also mildly alcoholic, creating a potent cocktail for the wa wasps that pollinate the plants. Stupefied wasps crawl sluggishly across the helleborine flowers, and linge linger on them for much longer periods of time than one mi might expect. Botanists have speculated that this may help to ensure that the wasps deliver helleborine pollen to an another helleborine flower, rather than flying to an another plant species and potentially wasting th their orchid pollen payload. Our orchids ar are found in a host of habitats, from open
grassland to saturated fens, and from acid moorland to the deepest, darkest of woodlands. There is barely a habitat in the British Isles in which at least one orchid species will not be found. Some, particularly those found on woodland floors, have dispensed altogether with the need to photosynthesise. Instead of producing their own food from sunlight, they rely on other plants to do it for them.
WOOD-WIDE WEB
Orchids such as the bird’s-nest orchid are mycotrophic, using fungi rather than photosynthesis to provide them with their food. Lacking chlorophyll and hence green leaves, their roots are infected with the Sebacina fungus their seeds require if they are to germinate. Sebacina fungi have a symbiotic relationship with the trees that grow about them – their mycelium connect to the tree roots, and draw carbohydrates from the trees and, in return, provide minerals to the tree. Bird’s-nest orchids hack the wood-wide web, drawing their nutrients from the fungus.
Meanwhile, another orchid has more refined tastes still. Recent research has shown that narrow-leaved helleborines draw their nutrients exclusively from truffles found beneath the forest floor. Truffles currently enjoy a reputation as an aphrodisiac, but for centuries some of our native orchids were considered the Viagra of the vegetable world.
Since Greek botanist Pedanius Dioscorides wrote about them in AD65, until they fell from fashion in the early 19th century, the tubers of certain orchids were held to be “a stimulus to Venerie”. The early English botanist Nicholas Culpeper, speaking about early purple orchids in 1653, warned that “the roots are to be used with discretion. They are hot and moist in operation, under the dominance of Venus, and provoke lust exceedingly.”
It was desire of a more wholesome and admiring kind that possessed me recently to devote a summer to seeing
THERE ARE PROBABLY MORE AMUR TIGERS THAN LINDISFARNE HELLEBORINES. .
every one of our native orchid species and exploring the stories connected with them. My travels took me to all ll corners of the British Isles. At the coastal extremities, ,I I gazed on orchids found nowhere else on Earth. Two such endemics include the Irish marsh orchids that lend western Ireland’s coastal meadows a purple hue, and the Lindisfarne disfarne helleborines that are unique to a corner of Holy Island. nd.
Lindisfarne helleborines were only recognised as a species in their own right as recently as 2002, based on genetic analysis. Their entire world population numbers bers just a few hundred plants, of which even in a good year ear only 300 will flower. They grow in sandy dune slacks, barely above sea level, and are vulnerable in the longer term to both climate and sea-level change. It’s a sobering thought that there are probably more Amur tigers left in the wild.
One of our native orchids, while not restricted to Britain alone, appears to enjoy flirting with local extinction more than any other. The ghost orchid has never been commonplace in English woods in the way that it is in other countries across its global range but here it has typically only ever been found in ones and twos. Years, sometimes decades, pass between sightings.
When, in 2009, wildflower conservation charity Plantlife formal formally declared that the ghost orchid was extinct as a British species, it had been 23 years since the last flowering plant had h been seen in the Chilterns. So it was both deeply unfort unfortunate and rather ironic that, unknown to Plantlife, just ju a few days before its declaration of the loss, an a amateur botanist had managed to find one flowering in a dark Herefordshire woodland. Since then, however, there has been no further sig sign of this most elusive of all our native orchids. Surely, were th there to be ghost orchids flowering in a woodland in recent summers, someone would have seen them?
BACK FROM THE DEAD?
It’s pos possible, however, that a combination of factors may be render rendering our woods less suitable for these blooms. Climate change is affecting the timing and nature of our seasons. The in increased frequency of storms may not help either, since they t topple mature trees in woodlands and remove the darkness dar that ghost orchids crave. And water abstraction may be drying out the soil in which the orchids grow.
I’d love l to think that my declaration that the ghost orchid may be lost to us will be swiftly followed later this year by one being be found in flower, though I’m not holding my breath breath. But in the meantime, I’d love to encourage people to keep their th eyes open for orchids in the coming months.
Not only are orchids fabulous, deceptive and beautiful, the stories attached to them are every bit as colourful as the flowers themselves. Nowhere in the British Isles is far from a nature reserve at which some of these blooms can be readily found. So wherever you might live, you too can enjoy an orchid summer this year.