By Alex Kirby BBC News Online environment correspondent

Scottish conservation groups and the police are joining forces in a campaign to stamp out the crime of stealing wild plants.

Snowdrops offer rich pickings

The campaigners are handing out postcards of bluebells, with the message Stolen from the Wild.

The cards tell people many favourite garden plants like bluebells and snowdrops are stolen from wild populations.

If the thefts continue, the organisers say, it could put entire species of plant at risk.

The campaign is being launched in Scotland by Strathclyde Police, Scottish Natural Heritage (SNH), the government's wildlife advisers, and Plantlife Scotland. It is called Paw - Partnership for Action Against Wildlife Crime.

The cards are aimed at everyone, especially gardeners, and will be distributed in garden centres and other likely picking-up points.

John Ralston of SNH said: "At this time of year people want to buy plants and hanging baskets for their gardens.

"But we want them to be aware they could be buying products which have been taken illegally or which are damaging the environment.

"We are concerned that many species, such as sphagnum moss, which forms a vital protective layer for peatbogs, are being plundered in large quantities by commercial pickers to fuel this trade."

Hard to detect

One case of sphagnum moss gathering recorded by police in south Lanarkshire caused around �34,000 of damage. A van-load of snowdrop bulbs seized in Fife was estimated to be worth �60,000.

The gangs involved are often linked to other wildlife crimes, as well as house-breaking, theft and drugs.

The native bluebell has foreign competitors

It is illegal to take plants from the wild without the permission of the landowner, and many species have additional protection under the Wildlife and Countryside Act 1981.

Phil Briggs of Strathclyde Police said: "We know that plant crime is going on throughout the country, but because of the remote locations where these gangs operate it is difficult to assess the scale of the operation.

"We would urge people to be more vigilant and suspicious of plant theft, particularly in the evenings and at weekends."

Britain's wild plants are also under threat from introduced invasive species, habitat loss and climate change.

Foreign invaders

The native bluebell is under particular threat from Spanish and hybrid bluebells, which have spread to the wild.

Plantlife is running a bluebell survey to see how widespread the three types of bluebell are.

Dr Deborah Long of Plantlife Scotland said: "People can help by contributing to the bluebell survey, and by taking the advice in the Stolen from the Wild campaign.

"For example, instead of buying moss to line baskets or mulch pot plants, why not use non-moss alternatives or moss raked from your lawn?"

The campaign wants people to check where bulbs come from and ensure garden hybrids and strains are far away from native populations to prevent hybridisation.