Mushrooms, genetically different from plants, are similarly immobile. Mushrooms contain no chlorophyl; most are saprophytes, meaning they gain nutrients from dead organic matter. Plants produce seeds; in order to reproduce themselves, mushrooms either spread to adjoining areas or disperse spores into the wind. Spores are light, usually containing only a single cell.
Male and female cells in a mushroom fuse to form spores that are necessary for sexual reproduction. Spores do not contain an embryo as seeds do and hardly any food reserves. To increase the chance of survival, an adult fungus produces millions of tiny spores. The mold on bread is composed of millions of spores, each growing on a tiny stalk.
When a single-celled spore lands in a moist, warm place, it swells, absorbing food through its cell wall. It divides into two cells, each of which absorbs food; these cells continue dividing, forming long chains of cells. These chains look like threads and are called hypha. A mycelium is a tangle of hypha that consumes rotting vegetable matter, continuing to grow until it becomes a mushroom.
Some fungi produce spores in a special cell that bursts, shooting spores into the air. Larger spores travel farther. The fungus Podospora fimicola produces only eight large spores that it can shoot up to 20 inches. Pilobolus can shoot a sticky mass of spores as far as 8 feet. The bird's nest fungus, Sphaerobolus, has a mass of spores that rest in a cup. When rain fills the cup, the sodden inner layer causes the cup to turn inside out expelling the mass of spores with an audible pop that can shoot it up to 13 feet away. Mushrooms with caps produce spores in the gills. How these spores are discharged is not completely understood.
Spores are smaller and lighter than seeds. There are more obstacles preventing them from spreading so mushrooms yield far more spores than plants produce seeds. When taller plants drop seeds, they are easily carried by the wind. Mushrooms grow close to the ground where there is little or no wind. Spores released in clouds depend on the wind for dispersal. The puffball is an example. Spores of wheat rust have blown more than 1,000 miles in the wind.
Other Means of Dispersal
Some mushrooms produce spores that float; these are dispersed by running water.
Spores are also spread by animals. Mature truffles have an aroma that attracts animals that dig them up and eat them; the undigested spores are spread in the animals' excrement. Stinkhorn mushrooms form a slime that smells like rotten meat. Flies feed on the slime and fly away carrying stinkhorn spores with them.