Maitake (Grifola frondosa), called hen of the woods in English, is a large clustered forest mushroom that grows not as a single capped stalk but as a sprawling rosette of dozens of overlapping, frilly, spoon-shaped fronds in smoky grey-brown shading to tan, fanning out from one branched base at the foot of old oaks — earthy, peppery and deeply umami, prized above almost all other mushrooms in Japanese cooking.