The fungus is native to the northeastern part of Japan and North America, and is prized in traditional Chinese and Japanese herbology as an adaptogen, an aid to balance out altered body systems to a normal level. Most people find its taste and texture enormously appealing, though the mushroom has been alleged to cause allergic reactions in rare cases.
Hen of the woods grows from an underground tuber-like structure, about the size of a potato. The fruiting body, occurring as large as 60 cm, is a cluster consisting of multiple grayish-brown caps which are often curled or spoon-shaped, with wavy margins and 2-7 cm broad. The undersurface of each cap bears approximately one to three pores per millimeter, with the tubes rarely deeper than 3 mm. The milky-white stipe (stalk) has a branchy structure and becomes tough as the mushroom matures.
Maitake, an edible mushroom of the (Polyporaceae) family, can grow up to over 50 pounds (20 kilograms), earning this giant mushroom the title "King of Mushrooms.". In Japan, maitake make up the 4 or so major mushrooms used in the country (other being shiitake shimeji and enoki. There are used in a wide variety of dishes, often being a key ingredient in nabe or cooked in foil with butter.
Maitake is rich in minerals (such as potassium, calcium, and magnesium), various vitamins (B2, D2 and Niacin), fibers and amino acids. The active constituent in maitake for enhancing the immune activity has been identified in the late 1980s to be the protein-bound polysaccharide compound, beta-glucan, an ingredient found especially in the family of polyporaceae.