The hericium erinaceus – or ‘bearded tooth’ – grows on just a few trees in the national park. The fungi is believed by some to have medicinal properties and is legally protected, meaning it is always illegal to pick, even for scientific purposes, without authorisation.

However, earlier this month, three bearded tooths were cut and taken away from their natural habitat.

Police in Hampshire have launched an investigation with the Forestry Commission and Natural England.

A spokesperson for the Forestry Commission said: “New Forest keepers and rangers will continue to ask local people and visitors not to pick fungi in the New Forest National Park and help spread the message.

“We encourage people to get out into the forest to enjoy the signs of autumn and people must act responsibly and leave rare fungi in their natural environment.”

The theft “highlights that there are still a few people who will take rare fungi from this special place,” the spokesperson said.

Officials are not revealing the locations where the bearded tooth fungi was taken. Some believe the mushroom, which grows on the trunks of hardwood trees, can assist in the management of Alzheimer’s disease and dementia.

As reported in the Daily Echo earlier this month, the Forestry Commission recently put up signs implying mushroom picking is completely banned in the national park.

Pickers criticised ‘misleading’ signage which reads ‘No picking’, and say they fear well-meaning members of the public will confront foragers.

Commercial picking is against the law under the Theft Act 1968, with anything over 1.5kg considered commercial.

Anyone with information about the theft of the fungi should contact police on 101.

The Forestry Commission spokesperson said: “We need people to report incidents to the police, not just on social media – otherwise it won’t be dealt with appropriately.”