Mushrooms are the fruiting bodies of fungi, which are neither green plants nor animals. They are related to mold, mildew and yeast. Most mushrooms grow and decay quickly. Some appear literally overnight.
Mushroom spores can take from a few hours to several days to germinate, according to MycoMasters. The fungal organism that produces a mushroom is called a mycelium. This organism secretes enzymes that digest organic matter. The mycelium eventually has enough energy to reproduce.
When conditions are right, the body of the mycelium starts to fruit or produce mushrooms. Factors affecting the growth of a mushroom from a mycelium include heat, humidity and day length. Fungus can live in soil or mulch for years and only produce mushrooms when conditions are right.
There are a variety of types of mushrooms. Mushrooms that grow in mulch can appear overnight. Mushroom growers cultivate certain species, and some are difficult to grow in any quantity. For examples, morels are among the most difficult to grow, and although the spores germinate quickly and the mycelium grow rapidly, it's difficult to get mushrooms to form, according to MycoMasters,