Meripilus Sumstinei: The Black Staining Polypore Mushroom

Meripilus sumstinei[i] is a large, multi-capped polypore that is interesting largely because it tends to be mixed up with other species. M. sumstinei is edible[ii], but few people enjoy it. If it has medicinal value, that value is yet to be researched or described. But the species is a close look-alike for Grifola frondosa (maitake or hen-of-the-woods), a choice edible famed for its medicinal value. Several other species, most of them also edible, also resemble this species to greater or lesser degrees. The problem is not so much one of accidental poisoning through misidentification (although foragers should use caution; dangerous mistakes are always possible) as the risk of wasted time and effort—and the risk of a mushroom removed from its environment for nothing.

Perhaps in keeping with the potential for ID confusion, M. sumstinei is also the center of a mixed-up knot of names. Part of the problem is that the species, which has an exclusively North American distribution, has a close relative in Europe, M. giganteus, and many authorities mistakenly apply the giganteus name to both. Some of the same common names, such as “black-staining polypore,” also apply to both.

Also, M. sumstinei’s look-alike, hen-of-the-woods, is often confused with chicken-of-the-woods solely on the basis of their names—the two do not closely resemble each other. Apparently as a joke, “rooster-of-the-woods” has been proposed as a common name for M. sumstinei, creating a whole flock of fungal poultry for mycophile tongues to trip over. The name seems to be catching on, as it appears on several websites.

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Meripilus Sumstinei Identification and Description

Cap: Each cap is medium-sized, fan-shaped, whitish when young and turning brown with age—bruising black when touched. The interior flesh is white and slightly stringy. Multiple caps grow in an irregular rosette from the same branched stem.
No gills—the spores are released from pores. Because the pores are very small, the pore surface looks very smooth. It is white to tan, and bruises brown or black when touched.
Tough, short, often off-center, white at first and darkening to brown with age.
Mildly pleasant
Mild to slightly acidic.
Smooth, elliptical to round
Spore color:
Edible, but not popular
Eats living or dead wood, mostly oaks and other hardwoods, though it has been reported on Douglas-fir. The fungus fruits from the base of its tree in the summer and fall.

Differentiating M. sumstinei from its several look-alikes in North America is not actually difficult, since it is the only one that bruises black when handled. The black bruising also adds to the perceived unpalatablility of the species; few people like to eat black food.

Meripilus Sumstinei Look-alikes

The main look-alikes of M. sumstinei are Grifola frondosa (maitake, or hen-of-the woods), Bonarzewia berkeleyi (Berkeley’s polypore), and Sparassis spatulata (cauliflower mushroom)[iii]. None are toxic, and of the group, M. sumstinei is the only one that bruises black. There are other differences.

  1. frondosa has small caps and the pore surface is grayish lavender when young, whereas M. sumstinei has larger caps and the pore surface is white when young.
  2. berkeleyi has large, thick, cream-colored caps with very large pores, especially close to the stem. M. sumstinei has thinner, smaller caps that are white to brown, and its pores are unusually small—the pore surface is notably smooth.

Sparassis spatulata has long, thin, folded, ribbonlike caps; the whole fruiting body resembles a giant carnation rather more than a cauliflower. M. sumstinei lacks the distinctive ribbonlike look.

  1. gigantea does reportedly look very like its American cousin, and does stain black, but there is little risk of confusion unless somebody plants some in North America and it escapes.

Meripilus Sumstinei Benefits

  1. sumstinei is edible, at least when young, but it is not popular. A few people do enjoy it, especially for making broth or meat substitute[iv]. Its nutritional profile is not known. It has no known medicinal application (yet).

Meripilus Sumstinei Dosage

Dosage is not an issue, since this species is not used in medicine.

Meripilus Sumstinei Toxicity, Safety & Side Effects

While M. sumstinei is generally considered edible, its close relative, M. giganteus, also reportedly edible,  sometimes causes gastrointestinal problems[v]. It’s likely M. sumstinei can have a similar effect.


[i] Kuo, M. (2010). Meripilus sumstinei.

[ii] Black-staining Polypore: Meripilus sumstinei (Formerly, M. giganteus). Missouri Department of Conservation.

[iii] Black-staining Polypore: Meripilus sumstinei (Formerly, M. giganteus)

[iv] Rooster of the Woods. Inside the Outside website, accessed March 31, 2020.

[v] Meripilus giganteus (Pers.) P. Karst. – Giant Polypore. First Nature website, accessed March 31, 2020.



7 thoughts on “Meripilus Sumstinei: The Black Staining Polypore Mushroom”

  1. I ate a little bit of it and had gas and mild nausea. It is not over yet, so am not sure how I will end up :0). Would not recommend it.

  2. I find this mushroom has a rich beefy flavor though the tough texture makes it hard to eat as is except the tips of the freshest finds. I prefer to use it to make a rich mushroom stock or to add flavor to other dishes. Chop and sauté the shroom with some onions then add plenty of water and simmer for 2-8 hours with any other good stock things like garlic carrots celery thyme peppercorn bay parsley, etc. strain then use for soup or freeze for later.


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