Fungi are very strange organisms. They have no stems, no roots or leaves. Even the most advanced of them are no more than interwoven threads. At first sight, they appear dead and early naturalists considered them exactly that. Fungi, the only organism apart from bacteria that can digest wood, feed on the fallen trunk of this tree in the forest, releasing the nutrients it contains. We know that their cells divide in a way that is fundamentally different from any other organism which sets them apart from both animals and plants into a kingdom that is entirely their own.