Bri­tish or­chids

Or­chids are spec­tac­u­lar, de­ceive in­sects for a liv­ing and de­velop amaz­ingly com­plex bonds with fungi. Jon Dunn falls un­der their spell.

BBC Wildlife Magazine - - Welcome - JON DUNN is a nat­u­ral­ist, tour guide and au­thor. His book Orchid Sum­mer (Blooms­bury, £15.95) is out now; www.jon­dunn.com.

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.

This chalk down­land in Kent is stud­ded with com­mon spot­ted or­chids. As their name suggests, th­ese or­chids are plen­ti­ful and flower through­out the Bri­tish Isles, from June to Au­gust.

The lady’s slip­per orchid is now thriv­ing in some of its for­mer strongholds thanks to botanists at Kew Gar­dens.

Below: de­spite their name, fly or­chids are pol­li­nated by dig­ger wasps. Right: bird’snest or­chids are yel­low plants, usu­ally found in wood­land.

In lizard or­chids, the lat­eral petals and sepals form the ‘head’, while the di­vided la­bel­lum cre­ates the ‘legs’ and ‘tail’.

The ghost orchid is Crit­i­cally En­dan­gered and one of the UK’s rarest plants.

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