Amanita muscaria
Fly agaric mushrooms of the kind found in the Queen's garden

As part of the promotion for a forthcoming TV programme, celebrity television gardener Alan Titchmarsh said he discovered Amanita muscaria mushrooms – commonly known as fly agaric mushroom – in the grounds of Buckingham Palace. He was exploring the Queen's private gardens for a show to be broadcast on Christmas Day.

Titchmarsh's remarks have been quoted in British newspapers.

"That was a surprise but it shows just how varied the species [of mushrooms] are," said the presenter of The Queen's Garden TV special. It is not really clear just why Titchmarsh was surprised, however, since the mushrooms are a common species.

The mushrooms contain psilocybin: a chemical that can cause hallucinations, and auditory and visual distortions that can make colours seem very intense, when the mushroom is eaten.

Some users report having spiritual experiences, which have led the mushrooms to having associations with Christmas.

It is claimed that Siberian shamans fed the mushrooms to reindeer, so that the poisons were filtered through the animals' livers and kidneys. The shamans are then said to have drunk the reindeers' urine in order to receive visions. Part of the ceremony included climbing through a chimney in their huts.

As well as being hallucinogenic – the fly agaric is toxic – effects can range from low blood pressure, nausea, twitching and drowsiness – although deaths from eating the fungus are rare.

A Buckingham Palace spokesperson said: "There are several hundred fungi species in the palace garden, including a small number of naturally occurring fly agaric mushrooms. As the programme explains, they are beneficial to trees, increasing their ability to take in nutrients." Royal officials also stated that no fungi from the garden are used in the palace kitchens.

Royal officials also stated that no fungi from the garden are used in the palace kitchens.

Possession of mushrooms containing the hallucinogen psilocybin is illegal in the UK, but the fly agaric does not fall into this category.