MycoNote is free, with no paid subscriptions. It runs on readers’ support. The site lives thanks to readers. Support the project →Support MycoNote →
Updated
The quickest way to tell a giant polypore from a hen of the woods is to press the pores on the underside: a giant polypore's pores soon bruise dark brown, then black, while a hen of the woods' pores don't blacken. Then look at a single frond: on a hen it's thin, about 5–10 mm, while a giant polypore's caps are 1–3 cm thick and much wider.
Hen of the woods (Grifola frondosa), also sold as maitake, is a good edible when young. The giant polypore (Meripilus giganteus), also called the black-staining or blackening polypore, is a different story: sources disagree on whether it's worth eating at all. If you've seen American pages about the "black-staining polypore", they describe a close North American relative, Meripilus sumstinei, but the blackening test works the same way.
Do the pores blacken? Touch or damage a giant polypore's pores and they quickly go dark brown, then black; old caps get streaked and blotched with black too. A hen of the woods' pores don't darken when pressed, though they can turn a little yellowish with age. This is the most reliable feature.
Frond size and thickness. A hen is built from lots of small fronds, 4–10 cm across and only 5–10 mm thick. A giant polypore's caps are 10–30 cm wide and 1–3 cm thick, several times thicker.
How the clump is built. A hen grows from a much-branched, whitish stem carrying dozens of small spoon-shaped, often curled fronds, a bit like a ruffled hen sitting on the ground. A giant polypore forms a rosette or tiers of fewer, larger, flat fans.
Colour. Hen of the woods is grey-brown to greyish, sometimes olive-tinged. Giant polypore is tan to chestnut brown with darker zones. Treat this as a supporting sign: an old hen turns more tan brown too.
Pores up close. A hen's pores are larger, 1–3 per mm. A giant polypore's are finer, 3–5 per mm, and hard to see without a hand lens.
Doesn't work
The tree. Hen of the woods is usually at the foot of oaks and giant polypore at beeches, but both turn up on oak and beech.
Doesn't work
The size of the whole clump. "Huge, so it's a giant polypore" doesn't hold: a hen can be 20–50 cm across, and in Ukraine they have been recorded up to a metre across. Compare single fronds instead.
Doesn't work
Colour alone. An old hen browns and can easily pass for a giant polypore.
Press the pore surface with a finger or scratch it lightly, then give it a little while. A dark brown to black mark means giant polypore.
Look at the edges of older caps. Black streaks and blotches give a giant polypore away as well.
Pick out one frond. Thin (5–10 mm) and no wider than your palm points to a hen. Thick as a slice of bread and wider than your palm points to a giant polypore.
Look under the clump. A branched, pale stem with masses of small fronds is a hen.
Keep the tree and the colour as extra clues only.
In Britain and Ireland a big brown rosette at the base of a park beech is far more likely to be a giant polypore. It's common across most of Britain and Ireland, while hen of the woods is uncommon and rather localised, usually at the foot of old oaks. Both peak in September and October, with hen of the woods records most frequent in October, so in autumn the pore test is worth doing on every clump.
You won't be badly poisoned, but you may not enjoy it. Sources disagree on giant polypore: some UK foraging guides call young ones edible after long, slow cooking, others advise against eating it, and Ukrainian guides list it as inedible. Some people get an upset stomach from it, and older ones are tough and sour. No toxin has been found and we couldn't find any reports of serious poisoning. Because it grows at ground level in parks, think about dogs and lawn treatments too.
In Ukraine hen of the woods is listed in the Red Data Book as vulnerable, with collecting and the felling of old oak woods named among the threats, and the law there doesn't allow picking it. The giant polypore isn't listed. So if you're foraging in Ukraine and find a grey-brown clump under an old oak that doesn't blacken, photograph it and leave it be.
Another frilly fungus at tree bases, the cauliflower fungus (Sparassis crispa), is much paler and grows at the foot of conifers. Our hen of the woods vs cauliflower fungus comparison covers it.
| Characteristic | Hen of the woods | Giant polypore |
|---|---|---|
| Edibility class | Hen of the woods: Edible | Giant polypore: Conditionally edible |
| Use | Hen of the woods: Cook fresh, Drying, Pickling, Medicinal | Giant polypore: Cook fresh |
| Cap colour | Hen of the woods: Grey, Brown | Giant polypore: Brown, Chestnut, Dark brown |
| Cap shape | Hen of the woods: Irregular | Giant polypore: Irregular, Flat |
| Cap surface | Hen of the woods: Smooth | Giant polypore: Velvety, Scaly |
| Taste | Hen of the woods: Mild | Giant polypore: Sour |
| Smell | Hen of the woods: Pleasant | Giant polypore: Odourless |
| Flesh colour change | Hen of the woods: No change | Giant polypore: Blackening |
| Stem | Hen of the woods: Rooting | Giant polypore: Rooting, Lateral |
| Substrate | Hen of the woods: Living tree, Dead wood | Giant polypore: Living tree, Dead wood, On wood |
| Nutrition type | Hen of the woods: Parasite | Giant polypore: Parasite, Saprotroph |
| Partner trees | Hen of the woods: Oak | Giant polypore: Beech, Oak, Linden, Poplar, Horse chestnut |
| Growth habit | Hen of the woods: Solitary | Giant polypore: In clusters from one base |
Same in both: season, size, hymenophore.