Mouldy lemon. Penicillium sp. fungus growing on a lemon (Citrus limon). The fungus has spread over the surface of the fruit, producing a network (mycelium, white) of fine filaments (hyphae). It has also produced spores (green/grey), which may spread to infect other fruit. The fungus penetrates downwards into the fruit, digesting and absorbing nutrients. Most or all of the fruit will have decayed within a few days.