is the network of thread-like hyphae that forms the vegetative body of a fungus and absorbs nutrients from its substrate.
Structure and growth
A mycelium consists of numerous microscopic hyphae that branch and intertwine to form a filamentous network. Hyphae are tubular cells bounded by a cell wall containing chitin and beta-glucans. In septate fungi, cross-walls called septa divide the hyphae into compartments, while coenocytic fungi have continuous cytoplasm with multiple nuclei. Hyphal tips extend by apical growth, secreting enzymes that digest organic material and absorbing the soluble products. The mycelium spreads through soil, wood or other substrates, exploring for new nutrient sources and responding to environmental cues. Some hyphae differentiate into specialised structures, such as rhizoids that anchor the mycelium or haustoria that penetrate host tissues. When conditions are favourable, parts of the mycelium aggregate to form reproductive structures like mushrooms, conidiophores or sporangia.
Ecological roles and applications
Mycelia play central roles in nutrient cycling by decomposing dead organic matter and releasing carbon, nitrogen and other elements back into ecosystems. Mycorrhizal fungi form symbiotic associations between their mycelia and plant roots, improving water and mineral uptake in exchange for sugars. Networks of mycelia can connect multiple plants, facilitating transfer of nutrients and chemical signals in forest communities. Pathogenic fungi use mycelia to colonise hosts, causing plant diseases such as powdery mildews and rusts. In biotechnology, cultured mycelia are used to produce enzymes, organic acids and pharmaceuticals. Novel applications include using fungal mycelium as a sustainable material for packaging, insulation and building composites due to its fibrous structure and self-assembling properties.
By building an extensive network of hyphae, the mycelium allows fungi to efficiently colonise substrates, obtain nutrients and interact with their environment. Its versatility underpins many ecological processes and emerging biotechnological innovations.
Related Terms: Hyphae, Fungus, Mycorrhiza, Basidiocarp, Spore