Tina Kilpatrick, of Mairehau High School, asks :-

What are the white lumpy bits on the top of red toadstools?

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

Like all forms of life mushrooms are wonderful products of evolution. Each one is superbly adapted for producing, protecting and dispersing billions of single-cell spores. In many mushrooms, but not all, the spores are produced over the surfaces of the gills which hang down below the cap.

The gills are therefore very important structures which need protection. As a mushroom begins life below the soil surface it must then emerge above the soil in order to disperse its spores into the wind. During emergence it needs to protect the delicate gills. In the case of the poisonous red-capped toadstool with white lumpy bits on top (which goes by the name Amanita muscaria ), the stalk, the cap and the gills below the cap are all surrounded by a thin white layer as the toadstool expands and pushes its way up above the surface. This membrane then breaks apart as the toadstool expands further and the gills are exposed to the air. Fragments of the membrane remain stuck to the attractive red cap.

The gills are therefore protected both from abrasion by soil particles as the toadstool emerges and also from being eaten by tiny soil animals. Other remains of this membrane can be found attached to the bottom of the stalk if the whole toadstool is carefully removed from the soil (but wash your hands afterwards!).

Further adaptations of this toadstool are: 1, that it is attached to the roots of trees by fine threads - in this way it gains sugars for its growth from the tree; 2, each spore is shot from the gill surface at just the right speed for it not to fly across to the gill surface opposite and get stuck there; 3, the cap of the toadstool protects the gills from rain and 4, the stalk holds the cap and gills up into the wind currents in order to disperse the spores.