A When people think of fungi, they usually picture mushrooms. Yet these are only the fruiting bodies of much larger organisms that live mostly underground as networks of fine threads.
B These threads connect with the roots of trees and exchange nutrients. Trees provide sugars, and in return fungi supply water and minerals. Some scientists believe that older trees may even pass resources to young seedlings through these networks.
C Fungi are also nature's main recyclers. Without them, fallen leaves and dead wood would build up on the forest floor. By breaking material down, fungi return nutrients to the soil.
D Humans have long relied on fungi. Yeast is essential for making bread and many drinks, and the first widely used antibiotic came from a mould. Today, companies are experimenting with fungal materials to replace leather and plastic packaging.
E Despite their importance, fungi are poorly studied. It is estimated that only a small fraction of species have been described, and many may disappear before they are discovered.