By Jonathan Amos
BBC News science reporter
Outrageously showy, notoriously fussy and surrounded by fawning admirers - it's no wonder orchids are sometimes referred to as the "supermodels of the plant world".
Common spotted-orchids resplendent by the roadside
It is difficult in a few, simple words to characterise this large family of flowers; even the experts will stop for a moment before launching into a long list of likely traits.
But somehow you just know an orchid when you see one. "Sexual" and "flamboyant" are words that often come to mind. And if someone says something or someone is "orchidaceous", you instantly get the picture.
There must be more than 20,000 species of orchid worldwide, and the horticulturalists have brought us thousands more hybrids.
They are the perfect plant present and the clever breeders have ensured their creations are now "ready to go" at every petrol station and supermarket.
Most of the wild species are to be found in the tropics, particularly the more outrageous flowers; but even in the cooler climes of Britain, we can boast an impressive collection of orchids.
The 50 or so recognised species are not all jaw-droppers, of course. Some are small, spindly, green things that we could all easily miss.
But there are plenty of gems with their own little piece of magic - like the fly orchid (Ophrys insectifera). Its flowers bear a remarkable likeness to an insect and it secretes a chemical signal that drives male digger wasps nuts.
The wasps try to copulate with the plant and get covered in pollen in the process.
And how about the lizard orchid (Himantoglossum hircinum), whose flowers have long, straggly lips that make them look as though a reptile is trying to climb inside the plant.
Like many of our other wild flowers, orchids have suffered under the intensive land management practices of the past 50 years. Ploughed, sprayed, out-competed, dug up, mown, undergrazed - they've seen it all, and their numbers and their ranges have retreated.
Botanists now consider orchids to be at very high risk, as revealed in the recently published The Vascular Plant Red Data List for Great Britain. About a quarter are in a really quite parlous state.
Need for mouths
I recently had the pleasure of walking the chalk downlands of East Sussex with David Lang, a retired vet and passionate orchid man.
His profession brought him right up close to the countryside and he longs for the return of agricultural polices that cherish the landscape.
"It's pretty depressing, especially for those species that grew in damp meadows; or little old pastures that were grazed. People are no longer farming stock. The cows and the sheep have gone," he said.
"The one thing that kept the countryside like it was, was the mouths going chomp, chomp. If you take those away, you find the coarse grasses and scrub coming in and the orchids and other interesting chalkland flora moving out.
For David, the passion goes back to his schooldays
"People are more aware now but trying to get councils not to mow their verges like billiard tables is like talking to a brick wall."
It is good to report that many of the conservation efforts are reaping rewards.
The spectacular lady's slipper orchid (Cypripedium calceolus), which was picked to near oblivion by the Edwardians and Victorians, and reduced to a single plant in Yorkshire, is responding well to a recolonisation project run by Kew Gardens.
More than 1,500 seedlings have been reared and put back in the places where it used to grow. The thinking was that the soil fungus with which the slipper has a symbiotic relationship would still persist in its old haunts. And so it has proved. Numbers are climbing.
Other efforts have not fared so well. The critically endangered red helleborine (Cephalanthera rubra), a tall, pink, woodland plant, continues its retreat despite sensitive management.
And the fen orchid (Liparis loeselii), which has received a similar push to that of the slipper, has also largely failed to respond to the good intentions of conservationists.
One reason why this hit and miss is occurring may be because we still have much to learn about the needs of orchids.
The fragrant orchid is widespread provided the land is grazed
It is possible we are not creating the precise habitat conditions required.
"I would love people to take more interest in the things that pollinate orchids; in some cases we don't know what the pollinators are," says David Lang.
"And now that people have got digital cameras with thumping big macro lenses, they can take good enough pictures for a lepidopterist or an entomologist to identify the insects that are doing it.
"That will influence the conservation strategy and the mosaic of habitats that we need."
The long quest
David has just completed a full colour guide to British and Irish orchids. He hopes it will fire a little enthusiasm in the amateur botanist whilst at the same time helping them to navigate these remarkable plants.
Each orchid species is featured on a double-page spread with identification and distribution information.
The burnt orchid is one of several species that has experienced a sharp decline
The colour pictures show the whole plant and close-up views; and the easy-to-read text includes notes on identification, habitat, pollination, and conservation.
For David, the book completes a very long journey. He caught the natural history bug at school; a classic case of a pupil inspired by a great biology teacher.
"But what really started it was finding a French book of watercolours in the biology lab library," he explains.
"It had all the orchids that would occur in Great Britain and I decided there and then that I would try to see them all. That was 1949 and since then I've travelled all over the UK. I've seen every one, save for the new one, the Lindisfarne orchid, on Holy Island."
Britain's Orchids is produced by English Nature, the UK government's independent wildlife advisor, and WILDGuides ltd. The book is priced at £15