Mycoscout The short answer
Press a cap edge and look at the pores. A black-staining polypore (Meripilus sumstinei in North America; the giant polypore M. giganteus in Europe) turns dark brown to black where it is bruised, cut or handled. Hen of the woods (Grifola frondosa; maitake) does not stain. The hen is a rosette of many small, thin, grey-brown fronds, 2–10 cm across, rising from a central branching white stem; the black-staining polypore is a rosette of fewer, larger, thicker fan-shaped caps, 5–20 cm across, whitish to tan with a dark edge. Both grow at the base of oaks and other hardwoods and come back to the same tree for years.
The limit: an untouched black-staining polypore is pale, and bruising takes a little time to show. Check staining, frond size, frond thickness and pore size together, not one of them.
Side by side
| Feature | Hen of the woods | Black-staining polypore |
|---|---|---|
| Whole cluster | 15–40 cm across (Kuo); 20–50 cm (First Nature); up to 3 ft and 5–10 lb in Missouri | Up to about 30 cm or more (Kuo); clusters to about 32 in (MDC); 50–80 cm in Europe |
| Individual caps | 3–14 cm (Kuo); 4–10 cm wide, 5–10 mm thick (First Nature); grey-brown to tan, faint zones | 5–20 cm (Kuo); 2–8 in (MDC); 10–30 cm and 1–3 cm thick in Europe; whitish to tan, darker at the thin edge |
| Underside | Pores white to pale cream, 1–3 per mm, running down the stem; lavender-grey when very young (Kuo) | Pores pure white when young, 6–8 per mm (Kuo), 3–5 per mm in Europe; so small the surface looks almost pore-less |
| Stem and base | A common branching white stem, often off-center | Very short, thick, fibrous or absent; a shared branched stem-like base |
| Flesh when cut or bruised | White, unchanging; pores do not bruise | Cap edge and pores bruise dark brown to black; stem goes blackish with age |
| Smell | Mild, pleasant, sweet when young | Not distinctive |
| Spore print | White | White |
| Host and growth | Base of living oaks and other hardwoods, and stumps; weak parasite, then saprobe | Base of living oaks and hardwoods, stumps, buried roots; beech is the main host in Europe |
| Season | September to November (Missouri); summer and fall | July to September (Missouri); late June to late September (UK) |
| Range | East of the Rockies, rare in the west; Britain and Europe | East of the Rockies, occasional in the west (M. sumstinei); Europe (M. giganteus) |
Features that do not separate them
- A rosette at the base of an oak. Both, and Berkeley's polypore and the cauliflower mushrooms too.
- Pores rather than gills. Both are polypores with white pore surfaces. MDC uses "pores, not gills" to separate the hen from the cauliflower mushroom, not from the black-staining polypore.
- White spore print. Both.
- Coming back every year on the same tree. Both do.
- Overall size. The size ranges overlap. A large hen and a small black-staining polypore can match.
- Color from a distance. The hen runs tan to grey to cream, and First Nature notes almost pure white hens occur. Color is only useful close up, after handling.
- Tan caps on an old specimen. Kuo says both are brownish by maturity.
Bruising is the feature MDC singles out: among the hen's look-alikes, none bruises black except the black-staining polypore. Pore size backs it up with a hand lens. The chicken of the woods, often confused by name, is orange and yellow and is covered on its own species page.
What happens if you get it wrong
Neither species is called deadly or seriously poisonous by any source we read, which is why this pair is about a spoiled meal and a sourcing disagreement rather than an emergency. MDC rates the North American black-staining polypore a good edible when young and fresh, using only the soft outer edges, cooked long and slowly. First Nature says the European giant polypore has been known to cause stomach upsets in some people and is probably best avoided. Kuo and First Nature agree the two are different species under confusingly shared names, so a UK forager reading US advice, or the reverse, is reading about a different fungus. Because the two sources disagree and the two species share one common name, this site does not rate the black-staining polypore edible: the verdict band reads "edibility unknown" for both continents.
For the hen itself, First Nature warns that mature specimens turn tough, leathery and acrid, and MDC advises using only fresh, tender portions and eating a small amount the first time. Stomach upset within hours after either species is a gastrointestinal reaction; symptoms that begin 6 hours or more after a meal point to something else entirely and need poison control (US 1-800-222-1222; UK NHS 111, or 999 if unwell).
Using an app to check a find
A photo of the whole rosette shows frond count and size, and a photo of a pressed cap edge, taken a few minutes after you press it, shows the staining. An untouched specimen photographed from above shows neither. Mycoscout leads with the edibility verdict, shows its confidence, and names the black-staining polypore as the hen's look-alike with the features to confirm in hand. It is not a clearance to eat. For a free check, iNaturalist adds human identifiers, and a local mycological society can handle the specimen; the what mushroom is this guide lists both routes.
Frequently asked questions
How do you tell hen of the woods from black-staining polypore?
Handle it and wait. Black-staining polypore pores and cap edges turn dark brown to black where touched or cut; hen of the woods does not stain. The hen's fronds are smaller (about 2 to 10 cm), thinner and grey-brown with a central branching stem; the black-staining polypore's caps are larger (5 to 20 cm), thicker and whitish to tan.
Is the black-staining polypore edible?
MDC calls the North American Meripilus sumstinei a good edible when young and fresh, cooked long and slowly. First Nature says the European giant polypore (M. giganteus) has caused stomach upsets in some people and is probably best avoided. The two names cover different species on different continents, so the answer depends on where you are and which source you trust.
Does hen of the woods bruise black?
No. Kuo says the pore surface does not bruise and the flesh is unchanging when sliced. MDC says none of the hen's look-alikes except the black-staining polypore bruises black.
What else grows in a rosette at the base of an oak?
Berkeley's polypore, thick-fleshed and cream colored, and the eastern cauliflower mushroom with ribbon-like folds instead of caps. Neither bruises black. In Europe, the wood cauliflower is paler and grows at the base of pines.
Sources
How we checked this page: the Mycoscout team cross-checked every edibility, toxicity and look-alike statement against the sources below on October 31, 2026. It has not been reviewed by a mycologist.
- Hen of the Woods (Maitake) (Grifola frondosa), Missouri Department of Conservation. Accessed October 31, 2026.
- Black-Staining Polypore (Meripilus sumstinei), Missouri Department of Conservation. Accessed October 31, 2026.
- Grifola frondosa, MushroomExpert.com (Michael Kuo). Accessed October 31, 2026.
- Meripilus sumstinei, MushroomExpert.com (Michael Kuo). Accessed October 31, 2026.
- Grifola frondosa, Hen of the Woods, First Nature. Accessed October 31, 2026.
- Meripilus giganteus, Giant Polypore, First Nature. Accessed October 31, 2026.
