Grifola frondosa

Grifola frondosa (also known as hen-of-the-woods, in Japanese, ram's head or sheep's head) is a polypore mushroom that grows at the base of trees, particularly oaks. It is typically found in late summer to early autumn. It is native to China, Europe, and North America.
Description.
Like the sulphur shelf mushroom, "G. frondosa" is a perennial fungus that often grows in the same place for a number of years in succession. It occurs most prolifically in the northeastern regions of the United States, but has been found as far west as Idaho.
"G. frondosa" grows from an underground tuber-like structure known as a sclerotium, about the size of a potato. The fruiting body, occurring as large as , rarely , is a cluster consisting of multiple grayish-brown caps which are often curled or spoon-shaped, with wavy margins and broad. The undersurface of each cap bears about one to three pores per millimeter, with the tubes rarely deeper than . The milky-white stipe (stalk) has a branchy structure and becomes tough as the mushroom matures.
In Japan, the can grow to more than , earning this giant mushroom the title "king of mushrooms".
Identification.
Some similar-looking species are toxic. Edible species which look similar to "Grifola frondosa" include "Meripilus sumstinei" (which stains black), "Sparassis spathulata" and "Laetiporus sulphureus", another edible bracket fungus that is commonly called chicken of the woods or "sulphur shelf".
Uses.
The species is a choice edible mushroom. Maitake has been consumed for centuries in China and Japan where it is one of the major culinary mushrooms. The mushroom is used in many Japanese dishes, such as "nabemono". The softer caps must be thoroughly cooked.
Research.
Although under laboratory and preliminary clinical research for many years, particularly for the possible biological effects of its polysaccharides, there are no completed, high-quality clinical studies for "Grifola frondosa" .