To Ralph Waldo Emerson a weed was 'a plant whose finer virtues have yet to be appreciated.' He would have enjoyed this handsome informative work, no conventional weed handbook but a Flora of the less common wild plants of arable land. Over the last 25 years, arable weeds, often now called arable plants to encourage farmers not to be so hostile to them, have declined more steeply than any other group of plants in the UK. This is true too of other regions of western and even eastern Europe. It is a nice irony that the specialized opportunist plants which once competed with crops are now themselves in decline and under threat.

An informative introductory section looks into the history, ecology, conservation significance and biology of the flora of arable land and how it developed alongside the evolution of crops and agricultural techniques. In an innovative view of an old subject, the authors even examine the cultural significance of arable weeds, quoting Shakespeare and noting places where medieval strip fields persist in today's countryside. The main section of the book has a wealth of pertinent data. Each of 100 species has a full-page colour photograph, clear and concise descriptive text, comments on similar or associated species, and distribution map and notes on habitat, soils, management, seed longevity and germination, life cycle, flowering time and reasons for decline. Line drawings draw attention to diagnostic features.

The book's value does not end there, for it also has an introduction to plant families, with simple keys - including common plants not treated here - to broad-leaved species and grassweeds. The fumitory (Fumaria) key is particularly welcome, as few botanists seem confident faced with these attractive plants - which have a small centre of evolutionary radiation in Britain and NW Europe. The last part of the book takes in a wide variety of useful information on the management and conservation of rare arable weeds, site case studies, appendices summarising native and conservation status, a selected bibliography and contact adddresses. This most readable, well laid out and modestly priced work will publicize the plight of arable weeds and be a practical basis for their conservation.

It is ironic that the wild flowers most dependent on farming should, in recent times, have suffered more from farm improvements than any other: the more arable land, the fewer the arable flowers. Twelve of the 66 plants listed in the Biodiversity Action Plan are flowers of cornfields and field margins. Some, such as Corncockle, Cornflower and Pheasant's Eye have travelled the existential path from familiarity to memory, or, if you prefer, from local abundance to near extinction. More recently, they have changed from weeds to 'targets', that is, things of value that the Government has decided we need more of.

Good accounts of arable flowers have been hard to come by, although some of them are in the Red Data Book or Scarce Plant Atlas. This excellent book is what we have been waiting for. It covers more than 100 declining arable flowers and grasses, each with full-page photographs, and notes on identification (including comparisons with similar species), distribution, habitat, soil-type, life-cycle and 'reasons for decline'. Better yet, there is lots of context, with informative sections on the development of our arable flora since the Iron Age times, on the way plants have adapted to the farm calendar of sowing and harvest, and a series of case-studies on how interesting arable communities have been conserved.

There are illustrated keys to awkward groups like fumitories, cornsalads and umbellifers, practical guidelines, useful addresses and websites, and some excellent graphics. The layout is clear, although less glossy paper would be better for field use, and the key characters of the plants should have been highlighted.

It was said the English countryside used to sparkle - its field margins would swirl with the colour from arable 'weeds'. Times have certainly changed. Our fields are now a monochrome - a very plain, rather bright green.

The 'unwelcome' plants that took their chances among the farmers' crops are now in full retreat. Mechanisation, herbicides and modern techniques of field management mean it is the crop that now chokes the weed and not the other way around. Traditional arable species have shown perhaps the greatest decline of all British plants in the last 25 years.

Corn marigold, corncockle and cornflower are names which we might all recognise - they are still in the national consciousness; broad-leaved spurge, fingered speedwell and pheasant's eye are perhaps less well known. But these are all plants now listed in the UK Biodiversity Action Plan. Indeed, arable plants constitute one fifth of the wild flora targeted for conservation action in the UK.

Friend or foe?

"The arable plants have a very close link with us, the human species," said Dr Phil Wilson, a conservation consultant who has just produced a guide to arable plants. "They've been with us since the beginning of agriculture 12,000 years ago. Apart from their simple biodiversity importance, they have historical and archaeological significance as well. They are also very beautiful", he told BBC News Online.

Emblems of a lost England

Modern industrial farming techniques have now pushed many arable "weeds" close to extinction.

More details

The brilliant reds, yellows, lilacs and pinks are certainly impressive but they are nicknamed arable weeds for good reason. Cornflowers (Centaurea cyanus) were said to blunt the reaper's sickle and corncockle (Agrostemma githago) made the bread taste bitter. When this correspondent mentioned the decline of arable plants to a wheat farmer friend of his, he got the terse reply: "Come into my fields and I'll show you some bloody weeds." Farming practices were developed to eliminate precisely these types of plants - and they have done it very effectively. New, vigorous crop varieties and the shift from spring to autumn sowing have befuddled the weeds. Herbicides knock back those arable plants that persist at the edges of fields and the combine harvester - a marvel of modern technology - can sort grain so efficiently that seed merchants can guarantee a virtually pure product for the following year.

Web of life

"Our fields are now a monochrome - a very plain, rather bright green," said Dr Jill Sutcliffe, the botanical manager at English Nature, the UK Government's nature advisory body. "And that's not a particularly healthy sign. A healthy countryside should be much more vibrant than that. We've gone a bit too far one way and we need to come back." When fields were not so big - when they had more hedgerows and other boundaries - the arable weeds would proliferate in that margin where machinery turned. In these corridors of chaos the insects would thrive and the birds would feast. Conservation groups have long remarked about the drop-off in farmland birds. It was not surprising, therefore, that when the most comprehensive survey of British and Irish flora in 40 years was released last September, it found the arable weed species had suffered the greatest misfortune.

European money

"What we need to do is recognise that these plants are part of a rich, biodiverse environment and we should not let species like this just go extinct," said Sir Martin Doughty, Chair of English Nature. "We've had perverse incentives for farmers to go into intensive agriculture when what we really want is a system of financial support that allows farmers to continue working efficiently but also maintain the environment. "Hopefully, the mid-term review proposals for the common agricultural policy that came out of the [recent EU agriculture ministers' meeting in Luxembourg] will give us that opportunity."

This would make it financially worthwhile for farmers to establish areas on their land where arable plants could succeed. Best practice methods include leaving stubble in the field for as long as possible, perhaps cultivating some margins at different times to the body of the field, and reducing herbicide applications at those boundaries.

"One of the great hopes in reversing this decline and even bringing back some of the extinct species lies in the ability of arable plants to produce seeds that can last in the soil for decades - perhaps more than a hundred years," said Dr Wilson.

Dr Sutcliffe added: "You see this where buildings have been demolished and the soil underneath is disturbed - these flowers that were in the seed bank under the buildings suddenly come up." The interrupted brome (Bromus interruptus), which is listed in the field guide as extinct, has been seen three times recently on sites of demolished farmhouses.

QUAINTLY named flowers like weasel's snout and shepherd's needle, which grow among farm crops, now account for one fifth of wild plants being targeted for protection, conservationists have announced.

A guide to more than 100 of Britain's arable plants, published yesterday, says flowers that were once common are now rare sights because of increasingly intensive farming methods.

Those species most at risk in Scotland include shepherd's needle, which is fast disappearing in East Lothian, pink dianthus, geranium and yellow globe flower. Other species, such as corncockle, are already considered to be extinct in Britain. Also threatened are common poppies, corn marigold and cornflower.

Arable Plants - a Field Guide, produced by the government conservation agency English Nature, but covering the whole of the UK, comes a year after a Scottish wildflower protection project reported more than 90 per cent of Britain's grasslands supporting such plants had disappeared since the 1930s.

Wildflower experts said farmers were using increasing amounts of pesticides and other chemicals, cutting back hedges and filling in boggy areas where plants thrived. These measures have been accompanied by the development of more vigorous crop varieties and a shift from spring-sown to autumn-sown crops, which have all spelled bad news for wildflowers.

Such moves have improved production and made the use of farm machines easier, but also decimated wildflowers. This has also had a knock-on effect on bees, butterflies and birds further up the food chain. However, increasing organic farming, and schemes such as the Scottish Wildflower Grasslands Initiative, are helping to give wildflowers a reprieve.

A spokeswoman for English Nature said of the threat to arable plants: "It seems almost perverse that, despite increases in the area of land under arable cultivation since the 1940s, these are the wild plants that have shown the greatest decline."

Douglas McKean, a British flora expert at the Royal Botanic Garden, Edinburgh, said: "These developments are promoting a monoculture - where there is a single plant species in fields. However, some farmers will be unaware of the effect this has on the wider environment."

Sir Martin Doughty, chairman of English Nature, said changes in farming had had far-reaching effects on wildflowers. Launching the guide at the Royal Botanic Gardens, Kew, London, he said: "The changes in the way we have grown crops over the past 60 years have altered the picture of our countryside."

"We have seriously affected the whole diversity of our countryside; the plight of farmland birds has been well documented but arable plants may have fared just as badly, if not worse. We need to ensure that agri-environment schemes take these species into account."

Jane MacKintosh, an advisory officer for grasslands at Scottish Natural Heritage, said work to restore grassland was still at an experimental stage in Scotland. She said techniques included re-seeding grasslands, improving grazing management and reducing chemical use.

The Scottish Executive last week announced a �10 million boost to its rural stewardship scheme, which provides grants to farmers for environmental protection projects. George Lawrie, of NFU Scotland, said: "The financial difficulties over recent years have made this funding all the more important in ensuring farmers can maximise their contribution to the countryside."

Alack! 'tis he: why, he was met even now.
As mad as the vex'd sea; singing aloud;
Crown'd with rank fumiter and furrow weeds,
With burdocks, hemlock, nettles, cuckoo-flowers,
Darnel, and all the idle weeds that grow
In our sustaining corn. A century send forth;
Search every acre in the high-grown field,
And bring him to our eye.
King Lear: Act IV, Scene IV

Weeds familiar to farmers since the stone age have been brought to the brink of extinction by 50 years of intensive farming, changing the character of the countryside.

Colourful weeds like cornflowers - once so common on arable land that Shakespeare rattles off their names in his plays - are now hard to find. Some are already officially extinct. Their disappearance is due to intensive agriculture with the use of herbicides, and the loss of half the country's hedgerows in 50 years, mostly in arable areas.

Yesterday, English Nature issued a field guide to 100 dwindling arable plant species in the hope that some of the rarest may be rediscovered and saved before it is too late. The guide was launched at Kew Gardens, where the seeds of some extinct plants are preserved. A field has been planted with many of the rarest species in order to create fresh seed.

The survival of these "weed" plants is also vital to the insect and bird life that feed on them. It has been estimated that 80% of Britain's butterflies need these arable weeds to survive. Many farmland birds such as partridges are suffering from a scarcity of insects with which to feed their young.

Dr Phil Wilson, author of the book, said: "We have lost part of our heritage - part of our culture. These flowers are within the memory of people still alive; they can remember fields full of cornflowers. Now there are a handful of sites in the country where they occur." Dr Wilson says he hopes that the guide will lead to more arable weeds being reported, adding: "Toiling across miles and miles of arable desert in Cambridgeshire in the hope of finding one cornflower still alive is not what the average botanist will do."

There is also concern at English Nature that genetically modified crops will make a bad situation worse, because their cultivation involves large doses of herbicides designed to wipe out other plants. The guide comments: "If GM crops lead to even more intensive management practices than are involved in growing conventional crops, then they could prove to be the last straw for many of our endangered arable plants, as well as the organisms that depend on them for food and shelter."

Despite the bad news, hope remains for some species that seemed to have gone. The Interrupted Brome (Bromus interruptus), which is classed as extinct, has been spotted three times on the sites of demolished farmhouses. The hairy grass species thrives on poor soils, and has been killed off by too much nitrogen on crops.

Dr Jill Sutcliffe, botanical manager for English Nature, said: "Seeds seem to have the ability to lie dormant deep in the ground for years and suddenly, given the right conditions, germinate. Sometimes where gas mains have been laid or houses demolished, long-forgotten flowers bloom." A classic example is the poppy, seen where ground is disturbed after a long interval. An example near Ely this summer has been attracting crowds."

This "cornfield" at the Royal Botanic Gardens, Kew, is probably now the only place in Britain where between ripening ears of wheat you can see the scarlet of poppies next to the intense dark blue of cornflowers and bright yellow of corn marigolds.

All of them have disappeared from much of the country as farming has been intensified. Yesterday at Kew, south-west London, a new field guide to arable plants, the wildflowers of old-fashioned cornfields, was launched. It served as a reminder of exactly what has been lost.

With their whimsical ancient names such as corncockle, mousetail, fluellen, fumitory, downy hemp-nettle and lamb's succory, they have music as well as colour.

Yet they are the fastest declining group of wild plants in Britain: they make up a fifth of the species targeted for special help on the national biodiversity action plan.

They are plunging in numbers in much the same way as farmland birds have done, and for similar reasons - the ripping out of hedges, the mass spraying of herbicides and pesticides and artificial fertilisers, the replacement of mixed farming by monocultures, the year-round planting of crops and all the other changes associated with modern agriculture in recent decades.

Understandably, to most farmers, the bright flowers are, and always have been, weeds. Jill Sutcliffe, the top botanist at English Nature, which is publishing the book, said that life had long been tough for arable plants. "It's always been an uphill struggle for them because the farmer wants a crop. But the difficulties have sharply accelerated in recent decades", she said.

Sir Martin Doughty, English Nature's chairman, said that the organisation was not advocating turning the clock back "to the age of horse-drawn vehicles in Constable's day". He said: "We want to strike a balance between agriculture and wildlife, and recognise that these plants are part of a richly biodiverse environment, and we should not be seeing them disappear."

The guide, written by Phil Wilson and Miles King, both botanists, describes 100 species of flowers and grasses of arable landscapes; many declining, several now on the verge of extinction, and a few that have disappeared. Heading the list of plants declared extinct in recent years is corncockle, a lovely deep pink flower, and the interrupted brome, a grass species. Close behind comes the cornflower, once ubiquitous but now known only from 15 locations in southern and eastern England. There are colour pictures and full descriptions of each plant.

The guide's authors think that arable plants have been a neglected group, partly because botanists are not very likely to search through a dense field of crops on the off chance of finding something the weedkillers have missed. The guide's purpose is to make possible a better idea of the true distribution of arable plants, by letting everyone concerned with the countryside recognise them - farmers in particular.

But it is not all bad news. Across Britain, the old wildflowers are returning as farmers join agri-environmental schemes that offer them incentives to leave certain areas, such as field margins, unsprayed. Sir Martin said: "We need to ensure that agri-environment schemes take these species into account. The plight of farmland birds has been well-documented, but arable plants have fared just as badly, if not worse."

FARMERS are being encouraged to grow wild flowers to brighten up the landscape and provide essential habitats for butterflies and birds.

A campaign was initiated yesterday by English Nature, the Government's wildlife advisers, who want to see plants such as the poppy and corn marigold thriving again. About 20 per cent of traditional species have been lost during the last 60 years.

The most likely area for the plants to thrive is in the South of England, below a line from the Severn in the West to the Wash in the East, where the soil is light and chalky.

As well as popular flowers such as the poppy, the English Nature conservationists are promoting lesser-known varieties with names such as weasel's snout, pheasant's eye and shepherd's needle.

They hope that reform of the Common Agricultural Policy will allow farmers to be paid for improving the landscape instead of filling it with sheep and cattle.

Sir Martin Doughty, chairman of English Nature, criticised the way farming practices had altered the appearance of the countryside. He said yesterday: "Before, we would have seen a glorious variety of colours across our arable farmland but now what we are more likely to see is a flat monotone."

He added that the disappearance of the plants was far more serious than just the loss of their aesthetic appeal. "We have seriously affected the whole diversity of our countryside."

Much of the problem is the over-use of herbicides to control weeds, and new patterns of farming which see fields sown through winter months instead of being left as stubble.

Jill Sutcliffe, English Nature's botanical manager, called on farmers to vary the plants they grow near crops. "We've got used to the bright green colour of the countryside, but where are the fields of red, blue and marigold?" she said. "They give such an uplifting view that some people even vary their routes home from work to look at the scenery."

The first task was for farmers to identify the species still growing on their land, then experts could advise them how to expand the stock or introduce new varieties. Ms Sutcliffe said, however, that she wanted farmers and gardeners to take care of the seed varieties they planted. "There are now only about 15 sites of the traditional cornflower left in the UK and we really do not want to encourage non-native species and hybrids," she said.

Corn cleavers is another endangered variety which is singled out for conservation. It used to be common throughout southern England but recently has been seen only in Cambridgeshire, Hertfordshire and Essex. It was last seen in Oxfordshire in 1985. In Hertfordshire it grows among spreading hedge parsley, corn buttercup, sherpherd's needle and prickly poppy.

Another rare plant is the broad-fruited cornsalad, which is believed to survive on three sites in Gloucestershire and Somerset. The tiny, five-petalled flowers are clustered on the plant and are usually white tinged with a pale pink. It, too, is usually found with other rare plants such as small-flowered catchfly and few-flowered fumitory.

Red-tipped cudweed is another priority plant and is believed to exist on just 22 sites in Surrey, Hampshire, Sussex, Essex, Suffolk, Norfolk and Gloucestershire. Its favoured habitat is grassland and it is often found growing next to clustered clover, hoary cinquefoil and small cat's ear.

A full list of the important plants and flowers is contained in a new study, Arable Plants - A Field Guide, which is published by English Nature and WildGuides and will be used to advise farmers.

Poppies, cornflowers and corn marigolds - they used to be a common and colourful sight growing among the crops in farmer's fields. But now, along with such curiously named flowers as weasel's snout and shepherds needle, these and many other once-widespread varieties are on the endangered list.

Conservation body English Nature warned yesterday that a fifth of Britain's wild plants are under threat. And it said the chances of seeing them in the wild were growing slimmer by the year. The flowers are being pushed out by increasingly efficient agricultural methods. The way farmers grow crops has developed in the last 60 years and totally changed the picture of our countryside, according to English Nature.

Increased use of fertilisers and herbicides, development of more vigorous crop varieties, and the shift from spring-sown to autumn-sown crops have all had an adverse impact on the farmland flowers. A guide to the rarest plant species, aimed at helping people recognise and conserve them, was launched yesterday by English Nature and WILDGuides, a publishing organisation which supports conservation. The guide, unveiled at Kew Gardens in South-West London, also includes farmland plants such as pheasant's eye, small alison and greater pignut alongside better-known native varieties. Also detailed are corncockle, small-flowered catchfly, spreading hedge-parsley and red-tipped cudweed.

Sir Martin Doughty, chairman of English Nature, said: 'The changes in the way we have grown our crops over the last 60 years has completely altered the picture of our countryside. Before, we would have seen glorious variety of colours across our arable farmland but now what we are more likely to see is a flat monotone. But this is far more serious than just aesthetic beauty. We have seriously affected the whole diversity of our countryside. The plight of farmland birds has been well documented but arable plants may have fared just as badly, if not worse. We need to ensure that agri-environment schemes take these species into account.'

The guidebook, Arable Plants - A Field Guide, contains information on more than 100 species of Britain's rare arable plants. It describes how they can be identified, where they can be found, when they flower and details on their habitat. The guide was launched in an arable area at Kew as part of its Go Wild summer festival, which aims to spread the conservation message.