Most of the mushrooms have a cap called pileus and a stem called stipe. The cap on its underside consists of gills which bear the spora producing structures. Important to the identification of a species are the properties of cap, the shape and colour of the gills, the way in which they are joined to the stem, presence or absence of sheath, scales and annulus ring etc. The most poisonous mushrooms are species of Amanita which come under the family Amanitaceae and the most delicious edible mushrooms are species of Agaricus (Button mushroom) which come under the family Agaricaceae. In general the fruit bodies of Amanita species can be distinguished from the Agaricus species by the following characters.
In Amanita species the pileus on its upper surface bears the scales and the stipe bears at its base a sheath called Volva. These scales and sheaths are absent in the fruit bodies of Agaricus species.
Volvariella (Paddy straw mushroom) is also having Volva at the base of the stipe as in Amanita. But it is an edible mushroom and also commonly cultivated. The Oyster mushroom namely Pleurotus is another edible one. This can be identified by its stem at the side of the cap and gills on the under surface of the cap. Boletus (Penny bun mushroom) and Lactarius (milk cap) are also edible members which grow in wild condition but not cultivable. Among these Boletus can be identified by its dense layer of tubes instead of gills on the underside of the cap.
The familiarity in distinguishing the poisonous and nonpoisonous mushrooms is needed only when we collect the wild fungi from the field for our diet table. But this problem will not arise in the case of edible fungi which are cultivated for this purpose.