Mushrooms as Fungi
Related to molds, mushrooms cannot produce their own food through photosynthesis. They require decaying matter from which to draw their nutrients, but some varieties of mushrooms exist on living tree roots from which the mushroom gets its food and returns minerals to the roots of the tree. Since they do not conduct photosynthesis, mushrooms do not have the chlorophyll that green plants do. This makes mushrooms capable of growing in the dark as long as they can take advantage of a nearby plant or the decaying remains of one.
Mushroom Growth in Nature
Similar to the roots of the mushroom, the hyphae stretch out under the soil beneath the mushroom. These draw nutrients from the soil for the growth of the mushroom. Reproduction of the mushroom occurs after nutrients from the hyphae sprout a mushroom above the surface. Water fills the mushroom, swelling it. Most mushrooms have a stem topped by a cap with gills on the underside of the cap. The cap opens up as the mushroom swells and grows in size. This forces the gills open. Reproductive spores, located in the gills, get released into the air and blown by the wind until they settle onto another area of decaying plant matter to grow a new mushroom.
Toxic substances in the mushrooms prevent animals from eating them, but they also can prove fatal to humans who consume the inedible varieties. For safety, people should only consume commercially grown mushrooms rather than those found in the wild.
Commercial Mushroom Production
To produce large amounts of edible mushrooms, produces cultivate spores on plant matter. This material, mixed with manure and sterilized, provides the bed for many commonly seen types of mushrooms sold in stores. Shiitake, oyster and button mushrooms sold in stores most likely began in cultivated beds, but some varieties--such as truffles, porcini and chanterelles--must have annual wild harvests as commercial attempts to cultivate these proved unsuccessful.