The book of guidelines has been written specifically for land owners, scientists and casual gatherers who organise fungus forays.

But government advisers at English Nature, who have compiled the code, hope commercial mushroom pickers will also follow the guidelines.

They are increasingly concerned over reports that van-loads of wild mushrooms have been removed to be sold at specialist shops and restaurants.

The guide warns people not to pick species they do not intend to eat, and to be aware that some fungi are highly poisonous.

Eco-system threatened

Mushrooms play a vital part in nature's eco-system.

They break down dead animals and plants into food needed by other animals and living plants.

More than 1,000 species of insects and animals rely on mushrooms for food and shelter.

English Nature has warned if over-picking continues the survival of these creatures will be threatened.