Macro-photograph of mould on a slice of bread. Spores are abundant in the air and will readily infect a favourable medium such as damp bread. They germinate and produce an extensive network of thread-like hyphae which absorb nourishment for growth. Each mass of hyphae, called a mycelium, soon generates aerial branches called sporangio- phores which contain fruiting bodies responsible for the characteristic colour of the colony; green for Penicillium, blue, green or yellow for Aspergillus and black for the 'pin moulds' of Mucor & Rhizopus nigricans. The fruiting bodies, called sporangia, eventually rupture & the mature spores within are carried away by air movements.