Grifolaceae

One of the smallest families here, and honest about it: the Grifolaceae is essentially the genus Grifola, and its medical interest is essentially maitake. The fruiting body is distinctive — a large clustered rosette of overlapping grey-brown fronds at the base of oaks, sometimes reaching many kilograms, regrowing in the same spot for years.

Its taxonomy has moved. Meripilus giganteus, the giant polypore, was long treated as a Grifola and is still met under that name in older literature; it now sits in its own family. Where a mid-century source describes Grifola gigantea, it is not talking about maitake.

Maitake is one of the better-evidenced medicinal mushrooms, and its evidence is unusually specific. Its β-glucan fractions — the D-fraction and the more refined MD-fraction — carry the immune signal, acting through dectin-1 and complement receptors rather than any direct cytotoxicity.

The most interesting human result is not immunological at all. A small trial found maitake extract induced ovulation in polycystic ovary syndrome, at rates broadly comparable to clomiphene. That is a striking finding from an unexpected direction, and it remains small and unreplicated.

Grifolan, a β-1,3-glucan with β-1,6 branches, is the family’s characterised polysaccharide and the basis of the D-fraction preparations. Ergosterol, ergothioneine and a range of proteoglycans are present, as in most polypores. The family has no distinctive alkaloid or triterpene chemistry — the polysaccharides are the whole of it.