Mushrooms belong to a separate group of organisms called Fungi. They lack the green matter (chrolophyll) present in plants and grow on dead and decaying organic materials. From these decaying substrates, they absorb their nutrition with the help of very fine thread like structures (mycelium) which penetrate into the substratum and are generally not visible on the surface. After the mycelium has grown profusely and absorbed sufficient food materials, it forms the reproductive structure which generally comes out of the substrate and forms fruiting body, commonly known as mushroom. The mushroom fruiting body may be umbrella like or of various other shapes, size and colour. Commonly, it consists of a cap or pileus and a stalk or stipe but others may have additional structures like a veil or annulus, a cup or volva, performing various functions in the life-cycle of the fungus.