Betty Adams, of Millers Flat, asks :-

Could you please tell me something about this bright red mushroom with white spots on it which we found on our property? I have never seen anything like it before. We presume it is poisonous.

Paul Broady, a botanist at the University of Canterbury, responded.

You have found the most distinctive of all mushrooms. However, you have been beaten to it! The earliest known picture is in a fresco in a ruined church in France dating from 1291. It is poisonous, though I read “unlikely to be fatal”.

It is commonly known as the Fly Agaric and the scientific name is Amanita muscaria. A 13th century bishop, Albertus Magnus, recommended it as a fly killer when broken up in milk. Recent experience suggests that it is not very effective. Various religions have used it to stimulate hallucinations. The Hindu religion originated from one of these in about 1,500 b.c.e. Hallucinations can be accompanied by very unpleasant symptoms including twitching of the limbs. All mushrooms are sexual spore-producing structures of fungi and most are from a group called the basidiomycetes. The mushroom is a small part of the fungus the greater part being invisible underground or, for instance, in the wood of a decaying log. This part is called mycelium and consists of microscopic hair-like filaments that branch and fuse to form an extensive network. In many fungi this mycelium is active in decomposition of organic materials such as dead leaves and wood which form the food of the fungus.

The Fly Agaric obtains its organic food in a different way. It attaches to the roots of trees in a mutualistic symbiosis. Symbiosis refers to two types of organism in a close relationship, and mutualistic means both partners benefit. This symbiosis is an ectomycorrhiza. The fungus (-myco-) ensheaths the terminal roots (-rhiza) of the tree without penetrating into the root cells (ecto-, meaning outside). It gains sugars transported to the roots from the leaves and the tree receives water and mineral salts such as phosphate (fertiliser!) that the mycelium absorbs from the soil. The mycelium is more effective in this than are tree roots alone. Our vast plantations of Pinus radiata would be a shadow of themselves if it was not for the fungi associated with the tree roots. These provide more of the vital fertiliser and help the trees survive drought.

The Fly Agaric is another of those many plants, animals and microorganisms introduced into New Zealand by humans, in this case by Europeans. In Europe, it is common associated with birch and pine trees as is also the case now in New Zealand. It has started to invade our Southern Beech (Nothofagus) forests and seems to be displacing indigenous ectomycorrhizal fungi including a close relative called Amanita nothofagi. The health and nutrition of the trees might be affected. It also associates with the teatrees, Kanuka and Manuka.

Fly Agaric, like other mushrooms, is fantastically well-adapted for producing, protecting and dispersing spores. The white flecks on its bright red cap are the remains of a membrane that once completely enclosed the mushroom as it pushed up through the soil. There is also a ring-like flap of white membrane around the stalk which is the remains of another protective membrane. These membranes protect the spore-forming gills below the cap from being eaten by insects. The cap protects the gills from rainfall. The stalk lifts the gills into the air currents. When the mushroom has fully opened, spores are shot off the gills and then drop gently down into the breeze. They fall in their millions for a day or two. It seems wasteful but on average only one of these spores will grow and successfully produce more mushrooms. If all developed we would be submerged in mushrooms! Important! Be absolutely certain that a mushroom is not poisonous before eating any collected from the wild. For instance, the deadly poisonous Amanita virosa, the Destroying Angel, can be mistaken for the common edible mushroom!