The mushroom is the fruiting body of a plant, the part of a fungus that typically appears above ground and contains its reproductive units, or spores. Although mushrooms are usually considered members of the plant kingdom, they differ from most plants in that they lack chlorophyll and must rely on organic material for nutrition.
They do this in three ways: as saprophytes, as parasites, and as mycorrhizae.
1) Saprophytes live on dead organic matter, including dead wood, the dead tissue of living trees, dung, leaf litter, or conifer liter.
2) Parasites attack living plants or animals.
3) Mycorrhizae mushrooms have a symbiotic relationship with plants, usually either trees or shrubs. The mycorrhizal mushroom sheaths the roots end of the flowering plant, expanding the plants root system; the mushroom receives necessary carbohydrates from the tree.
Parts of a mushroom
Cap: The cap is the most conspicuous part of a mushroom and its shape can be important in identifying different genera. At first, many mushrooms caps are nearly round, conical, bell-shaped, or convex. As most species mature, the caps become broadly convex, flat or develop uplifted edges. Caps may be dry, moist, sticky, or slimy when they are fresh. A sticky or slimy cap may appear dry when it is old or dried out. In addition to be wet or dry, cap surfaces may be smooth and hairless, powdery, granular, or adorned with radial lines, hairs, scales, or veil remnants.
Gills: are plate-like structures on the underside of the cap; they radiate out from the stalk and produce the spores. In many mushrooms, the gills run down the stalk slightly or deeply. In some, the gills pull away from the cap as it expands; these are referred to as seceding gills. Most gills have thin edges that may be minutely fringed, toothed, or colored differently from the rest of the gills.
Stalk: Most gilled mushrooms have a stalk, usually located at the center of the cap; some are off-center or attached at one side. In a few cases where the stalk is absent, the mushroom usually grows on wood. The stalk surface may be smooth, dotted, lined, netted, scaly, powdery, or hairy. Stalks may be hollow, solid or filled with cottony tissue. Many species have a ring, a skirt or band-like tissue, or a zone of fibers on the stalk left by the partial veil as the mushroom expands.
Veils: Some mushrooms have veils, membranes that cover and protect either the entire immature mushroom or the immature gills. As the mushroom enlarges, the membrane ruptures, usually leaving traces on the cap or stalk. A membrane that encloses the immature gills on the unexpanded cap is called a partial veil.
All mushrooms produce millions of spores that are dispersed in various ways.