The morphology of filamentous fungi The filamentous fungi consists of two pats: the mycelium and the spores. The filamentous fungi develop multicellular branching structures known as hyphae, which are connected filaments of vegetative cells. Integrated masses of hyphae are called a mycelium. Each hypha is about 5-10 um wide.The morphology of filamentous fungi The filamentous fungi consists of two pats: the mycelium and the spores. The filamentous fungi develop multicellular branching structures known as hyphae, which are connected filaments of vegetative cells. Integrated masses of hyphae are called a mycelium. Each hypha is about 5-10 um wide