Macro-photograph of mould on a rotting apple. The brown rot in apples is due to Monilia fructigene, a fungus which germinates on any damaged tissue. The coloured blooms of mould belong to Penicillium and other species of the order Plectascales. The air-borne spores alight on the fruit & germinate. They absorb nutrients for growth via radiating filaments called hyphae. Each mass of hyphae, called a mycelium, generates aerial branches bearing fruiting bodies consisting of new spores. These appear green in the case of Penicillium and green, blue, yellow or black in the case of other Plectascales. Monilia fruiting bodies are white. The new spores are dispersed by air movements.