The Fairy-Tale Mushroom That Feeds a Forest

Fly agaric is probably the most recognisable mushroom in the world: a scarlet cap scattered with white flecks, standing alone on the forest floor. It's the toadstool of fairy tales and garden ornaments, but most of what makes it interesting happens out of sight.

A partnership with trees

Fly agaric is mycorrhizal. Its fine underground threads wrap around the roots of birch, pine and spruce, and the two trade: the fungus gathers water and minerals from the soil, and the tree pays it in sugars made from sunlight. That's why you almost always find fly agaric near those trees, and rarely out in open grassland.

Where the white spots come from

A young fly agaric pushes up through the soil inside a thin protective veil. As the cap expands, the veil tears apart and the fragments are left behind as those familiar white warts. They're only loosely attached, so a heavy rain can wash a cap almost clean.

Photographing red in the dark

Under a dense canopy, the forest floor can be very dim, even at midday. Exposing for the bright cap and letting everything else fall into shadow is what gives this mushroom that lit-from-within look, with no flash, just a patch of light and a lot of darkness around it.