Berkeley’s Polypore (Bondarzewia berkeleyi)

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New pics added 12-31-2019:

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New underside pics added 8-10-2019:

Growth Studies:

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Original pics:


New pics added 8-3-2019:

berkeley's polypore

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New pics added 7-27-2019:

Original pics:

New pics added 7-14-2019:

Three around a large oak tree…



Bondarzewia berkeleyi, commonly known as Berkeley’s polypore, or stump blossoms, is a species of polypore fungus in the family Russulaceae. It is a parasitic species that causes butt rot in oaks and other hardwood trees. A widespread fungus, it is found in Africa, Asia, Europe, and North America.

Elias Magnus Fries described the species as Polyporus berkeleyi in 1851. It was moved to the genus Bondarzewia in 1941.

The fan- or shelf-shaped caps grow in overlapping clumps from the bases of oak trees, each capable of growing to 25.5 cm (10 in) diameter. They are various shades of white to pale grey, cream, beige or yellow. The pore surface is white, as is the spore print. The round spores are 7–9 by 6–8 μm and have marked amyloid ridges. The tough white flesh can be up to 3 cm (1.2 in) thick and has a mild taste, which can be bitter in older specimens. The outer edges that cut easily with a knife are quite tender. Although Bondarzewia berkeleyi has been compared to eating shoe leather, it is edible, and can be used to replace or strengthen other flavors in dishes, much like tofu. It can also reportedly be used as a meat substitute.

In China it has been recorded from Guangdong and Hunan provinces. The fruit bodies appear over July to October in the United States. A survey of host trees in North Carolina found that it almost always grew on oaks, being recorded from the white oak (Quercus alba), scarlet oak (Q. coccinea), southern red oak (Q. falcata), chestnut oak (Q. prinus) and eastern black oak (Q. velutina), as well as bird cherry (Prunus pensylvanica).


A survey of host trees in North Carolina found that it almost always grew on oaks, being recorded from the white oak (Quercus alba), scarlet oak (Q. coccinea), southern red oak (Q. falcata), chestnut oak (Q. prinus) and eastern black oak (Q. velutina), as well as bird cherry (Prunus pensylvanica).


Yes, when young.

 Similar Species: 

Bondarzewia guaitecas (found in South America)

Preserving (Drying or Freezing):

Freezes well.

Dried: I see a lot of potential here.  When dried, the “pores” are so fragile as to easily crumble and powder with one’s fingers.  A mushroom powder can be made of the flesh as well, especially with a grinder or good blender.  A chef tasted a bit of this powder with me and concurred it is quite impressive.  I don’t think we compared the pore taste vs. the flesh taste.  We talked about adding it to recipes, honey (think of truffle infused honey, he described), and I thought of adding it to bread flour and even pasta dough.  I seemed to have noticed some of the spicy hot flavor remained in the dried.  Would that turn to bitter in baking?  If so, extra sugar may be recommended.  How about adding it to a salad (arugula-like spice w/o needing any plant additives)?  If so, how much can be added w/o gastric upset?  I do know that w/related mushrooms that are known to be intensely hot (the habanero of the mushroom world, being Russula emetica, other hot Russulas, & several intensely hot Lactarius sp.), they can be powerful GI irritants even when cooked (unless thoroughly cooked such that the hotness dissipates, I say in conjecture).  However, Russula emetica is said to be used sparingly as a raw powder as a spicy condiment, but I’ve not seen anything definitive on how they can be best dried while still retaining their heat.  I’ve also found with a hot Russula and a hot Lactarius, that keeping them refrigerated for days does appear to dissipate their heat.  So, the best potential for keeping the heat in a powder is to dehydrate right away.

J. Thinly Shaved like Truffles: I once knew a chef in Old Lyme, CT who said he used them like truffles, making shavings out of it.  The flavor profile is much different, but I can see how he could have done this well.  I’m sure the specimen & part of it make a big difference in how well this works, as well as how thinly it is sliced.  I don’t know if he ate it raw* or not.
K. Infusing: No matter how tough, spicy hot, or bitter, infusing may hold another excellent potential of this mushroom.  Examples of what it could be infused into include: Oil, vinegar, honey, vodka, maple syrup, and sugar syrup.  Please contact me with results of any of these methods.  I can say that I’ve infused maple syrup (really just boiled it in) with a mushroom that is extremely bitter (one not related to this mushroom), and the result was very impressive (quite a good number of people have now tried it from around the country).
L. Boiled and then:
1. Saute: All I have left from my original ~20lb find that’s not dried is a very tough mostly core section.  I have read that in Eastern Europe people have enjoyed a related species by boiling it and then working with it in various ways.  Knowing the remaining “pores” would still be tender, I cut some of them off and boiled them for 15 minutes.  Then I sauteed them in olive oil until crispy.  The texture was quite good, and the flavor was mild w/mild bitterness.  It was okay.  That is, until I took a spoon of these and poured some white balsamic vinegar on them.  The result was good!  The vinegar negated the remaining bitterness, while the crispy quality remained.  So, a crispy good experience.  It reminded me of my favorite soup, west lake minced beef soup with black vinegar.  I bet these would be quite good on top of the soup to add texture, a bit of flavor, and nutrition.
2. Pickle: Pickling can sometimes have a softening effect on texture especially over time, so storing them as pickles may work well.  Plus the acid used would negate the bitterness.

Recipe Suggestions:

I. Aroma: Especially on the day found, and holding true for some people many days later, this mushroom has a distinct and potent aroma that is also especially pronounced when dried.  I also recently left out slices overnight at room temperature, and alarmingly went to see if it was possibly spoiled.  Surprisingly, it smelled a bit like freshly baked bread!

II. Taste: They range from fairly mild, useful for soaking up any flavor around them, to very strongly flavored (best used as a seasoning, not a main course).  The latter including an interesting bitterness that comes through only when cooked.  In fact, when eaten raw*, some are very spicy hot (like a cross between arugula, radishes, and jalapenos).  The spicy hot effect takes about 30 seconds to kick in.  Fascinating (please see the Russula comparison section of this site for more information).

III. Texture:   Immature they are quite tender.  Mature, the edges can be quite meaty.  Yet the older they get, the tougher they become (with the more inner sections as toughest).  So far I have not encountered any my teeth could not handle, but I have yet to try chewing the most inner sections of my most mature finds.  The textural experience is comparable to chicken of the woods mushrooms, in that both become very tough in age, but chicken of the woods becomes not quite as tough, and is much drier.

IV. Other:
A. The largest one I’ve seen was a 40lb. specimen at the River Tavern in Chester, CT.  I was told it was being used, wasn’t too bitter [for their planned preparation], and a good amount of it was quite tender.  Perhaps their flavor and texture can vary considerably amongst individuals, with size not always being the determinant factor.
B. I believe I have discovered a direct correlation between how spicy hot they are raw and how bitter they will cook up.  It seems the spicy hot quality shifts to a bitter quality when cooked.  I suspect, as w/related mushrooms (please see Russula comparison page for more info.), that eating raw would cause GI upset if not done in small amounts, though conjecture would be that you can eat quite a lot more of this raw than you can with the very spicy Russula & Lactarius species.

V. Preparation of [Primarily Mature] Specimens: Ahead I list all the different ways of preparing I’ve heard of, including ways I’ve not heard of.  Also, different methods can net different results, so do try the different methods before deciding if your particular mushroom fits with your palate.  Remember this analogy: Cacao beans are bitter and a bit tough in texture, but when properly prepared we commonly get a very different finished product: Soft melt-in-your-mouth chocolate.  And so, it is sometimes not the bean or mushroom that becomes known for a particular culinary experience, but how the ingredient is used.
A. Mushroom Chips: Slice very thin (perhaps a peeler would do it, or on tougher specimens to use a meat slicer), then deep fry in hot oil.  Coat w/salt, vinegar, and possibly sugar.  This may render it crispy (think of how tough shrimp shells, and even smaller fish bones, go from tough to crispy via deep frying).  These mushroom chips are sure to surprise almost anyone when they’re told that they’re actually eating a mushroom!
B. Mushroom Steaks: Marinate tender sections overnight in a sweet & acidic sauce, then BBQ grill until crispy on the outsides.  NoteIf not using tender sections or a less mature specimen as pictured below, it will be like a very tough piece of meat, which most people will quickly tire of eating.

C. Braise: Chef John Schwartz of Niantic, CT suggested it may do well to extract its flavor by braising it for ~four hours.  This flavorful liquid can then be used in a variety of dishes (I’m thinking those that do well to also have acidic &/sweet sauces).  I’d expect this liquid to be very strongly flavored, thus best used in moderation amongst many servings.  In a followup I was told he braised it long-term, but additional braising did nothing for the texture, so he pureed it.  This puree was added to a minced lamb Bolognese sauce, and I had the opportunity to try it on pasta.  Delicious, and perhaps one of the best mushroom dishes I’ve tried.  The unique flavor was perfectly paired with the sauce’s other ingredients, and the pureed texture worked well with the lamb.  I suspect braising for much less time followed by a puree would work just as well.
D. Slow-Cooked: I found slow-cooking did not make it softer.  How strong this mushroom is to stand up to a slow cooker!  I think the best potential of this method is to extract the flavor.
E. Pressure Cooker: I have not tried this, but expect similar results to the slow cooker.
F. Meat Grinder: If getting mildly to moderately tough pieces, put through a meat grinder to end up with a nice product that can then be used in part to make meat-loaf.  Here’s a photo in my house of what it looks like after going through a meat grinder (once with the larger setting, then once through the smaller, so we get a more fine grind).  I added some of this to a vindaloo sauce.  Being strongly flavored and also that some pieces used were tough, adding it like a flavoring herb was the best use of it.

G. Blender: If using moderately to highly tough pieces, try pureeing it after chopping or grinding it.  Here’s a picture of the puree I did using my Vitamix blender.  I found my finished product incredibly potent.  To me, tasting it alone was like eating a strong spice, which should be used as a seasoning, not its own dish.  However, some peoples’ tastes are sure to disagree and what you see here would be a soup (with other seasonings added to it, such as soy, pepper, wine, or cream).

This paste can be use to coat salted chicken breast, baked in foil, then the foil removed at high heat to brown.  Yield is 100%, as all of the mushroom is used fully this way.  The flavor and texture work very well w/chicken in this way, as several of us tasters agreed.

H. Sauteed: Tender pieces can be sauteed without concern for them to get too soft.  More bitter pieces could be treated like bitter melon in a saute (sweet sauce, acidic, or for those who are into bitter, use some soy sauce and skip the sweet and/or acidic).


Bondarzewia berkeleyi