Zygomycetes (currently the phylum Zygomycota) are relatively primitive fungi characterised by the production of solitary spores, zygospores, as their teleomorph. Zygomycetes of significance here are characterised by hyphae with few if any cross walls (septa): the hyphae are essentially unobstructed tubes. Absence of septa facilitates rapid translocation of nutrients and organelles such as mitochondria and nuclei between sites of growth, nutrient adsorption and spore formation. In consequence, Zygomycetes are also characterised by rapidity of growth. Many species are able to fill a Petri dish with loosely packed mycelium and to produce mature spores within 2 days of inoculation.