Fungi are neither plants nor animals but belong to their own kingdom. They are unable to produce their own food through the process of photosynthesis, as plants do; instead, they acquire nutrients from living or dead plants, animals, or other fungi, as animals do. In many larger fungi (except lichens) the only visible parts are the fruit bodies, which arise from a largely unseen network of threads called ‘hyphae’. These hyphae permeate the fungus’s food source, which may be soil, leaf litter, rotten wood, dung, and so on, depending on the species, and take up nutrients.
The fruit bodies of beefsteak fungus are present from August to November (3). This parasitic species does not cause the timber of the host to weaken at first, but darkens the wood and produces an attractive pattern known as ‘brown oak’ (4), which is highly valued in cabinet manufacture and for other decorative uses (5). Beefsteak fungus is responsible for the hollowing of many oak trees (4).