Mycelium

Mycelium, the vegetative part of fungi which is not concerned in spore-bearing. It may consist simply of a much-elongated cell growing from the spore, or of a chain of cells, but in the majority it is a tissue of interlaced branched filaments or hyphae, loosely united in many moulds, membranous in dry-rot, compact and tuberous in mushrooms. See FUNGI.