Observation 156622: Polyporales sensu lato

When: 2013-12-29

Collection location: Rosslyn, Arlington, Virginia, USA [Click for map]

Who: Oregon-learning

No specimen available

This was Growing in a hole in a Maple Tree

The spores are white. There were lots of spores making an area of the hole completely white as can be seen in the second image

The underside of the cap has tubes or pores
As you can see from third and fourth images, the underside of the cap looks like a sponge.

As can be seen from the fifth and sixth images (side views of the underside of the cap) a side view of the spore distributing surface. There does not appear to be tubes. Could it be that they are so small that they can not be seen at this magnification

As indicated by images seven to nine, The spores are oblong and
6 to 7 by 13 to 15 microns

Finally as indicated by images ten and eleven The material in the cap is very fibrous

Is this a mushroom or something else

Species Lists


Growing in a hole in a maple tree
The spores are white — there were lots of spores
The underside of the cap is sponge like
Side view of the underside
side view of the underside
The cap is very fibrous
Here is a picture of the mushroom three weeks later on 12/29/13
I have also added pictures of the tree where it is growing
Here is a picture of the mushroom three weeks later on 12/29/13
I have also added pictures of the tree where it is growing
Here is a picture of the mushroom three weeks later on 12/29/13
I have also added pictures of the tree where it is growing

Proposed Names

47% (2)
Recognized by sight
28% (1)
Used references: Arora, Mushrooms Demystified, p. 565, under Bondarzewia montana. “Meripius giganteus occurs at the bases of hardwoods in eastern North America. It stains, ages, or dries gray to dark brown or black on the pore surface and/or margin and has much smaller pores (3-7 per mm). Like Bondarzewia, it often has a compound fruiting body, but has smooth, non-amyloid spores. The individual caps in all of these species are usually larger than those of Grifola.” All this may be true, but I have not seen it myself.
44% (2)
Used references: Arora “Mushrooms Demystified” page 565

Please login to propose your own names and vote on existing names.

= Observer’s choice
= Current consensus


Add Comment
By: Danny Newman (myxomop)
2014-01-04 00:51:20 PST (-0800)

that number is much closer to 100,000

Learning quickly, Oregon.
By: Daniel B. Wheeler (Tuberale)
2014-01-03 13:40:28 PST (-0800)

The USDA website covers those that are currently known. There could be others as well. Current estimates are for 1-2 million fungal species, of which about 200,000 have been named to date. We don’t even know what features to examine to figure what we should be looking at for new species.

By: Oregon-learning
2014-01-03 13:06:55 PST (-0800)

From some discussions with others, it seems to me that what we have is a polypore that has been invaded by a Hypomyces. Figure 7 probably shows smooth spores that are from the Hypomyces, and Figure 9 probably shows spores from the polypore. The United States Department of Agriculture web site indicates that nineteen different Hypomyces are know to invade polypores. The USDA web site is http://www.ars.usda.gov/Research/docs.htm?docid=10960

No spore measurements for
By: Daniel B. Wheeler (Tuberale)
2013-12-31 19:35:59 PST (-0800)

Meripulus giganteus in Aurora’s Mushrooms Demystified. He only states that the it has “…much smaller pores (3-7 per mm)” than Bondarzewia. One of the reasons I suggested Meripilus was the lack of spore dimensions in Aurora, who usually provides that data.

Question arises
By: Daniel B. Wheeler (Tuberale)
2013-12-31 19:28:58 PST (-0800)

were the conidiospores found from the original parasite on the oak, or was there a parasite on the fungus?

Regarding saving the tree: don’t think that is possible. Size of fungi indicates total basal colonization at minimum, with delignification and loss of structural integrity. Removal ASAP seems most sound.

Had a neighbor with the same problem earlier this year. He has a Mimosa tree (state tree of Hawaii, where his wife is from). Tree; was splitting at about 5.6 feet height. No sporocarps showing, but tree definately weakened. I advised removal, which was quickly accomplished. Turns out the visible decay was much deeper and more extensive the the outside damage could confirm. Saved him having a major portion of the tree fall on his roof this fall.

By: Ruzica and Sava Krstic (ruzasava)
2013-12-31 15:10:07 PST (-0800)

I got the material from Elmer, but it’s decayed so much that no original fungus tissue seems usable. The only recognizable thing are (tons of) septate conidiospores of some parasite. Their size (12-20 × 8-9) matches what Elmer found.

the very presence of a fruiting body
By: Danny Newman (myxomop)
2013-12-31 14:15:11 PST (-0800)

is indicative of mycelial colonization having become more or less systemic throughout the tree. a local arborist should have the last word on what to do. saving it is likely out of the question. it may also be at risk of falling.

How does one kill the mycelium of a mushroom like this to preserve the tree
By: Oregon-learning
2013-12-31 13:16:30 PST (-0800)

The mycelium for this mushroom is no doubt inside the tree.
How does one kill the mycelium in order to preserve the tree.
My guess is that removing the visible mushroom is not enough.

Collection preserved?
By: Ruzica and Sava Krstic (ruzasava)
2013-12-31 11:34:40 PST (-0800)

Elmer, if you still have some of the material, I could look at the spores and perhaps more.

Collection preserved?
By: Ruzica and Sava Krstic (ruzasava)
2013-12-31 11:34:40 PST (-0800)

Elmer, if you still have some of the material, I could look at the spores and perhaps more.

Tree is not Sweet Gum.
By: Daniel B. Wheeler (Tuberale)
2013-12-31 03:46:33 PST (-0800)

Nor is it maple. It is a variety of oak. With lobed leaves, it would fall into the White oak grouping. I am unfamiliar with Virginia oaks, so will leave it there.

The spores are not smooth? Seem angular in some photos, not angular in others.

Location added and response to other comments
By: Oregon-learning
2013-12-30 21:53:32 PST (-0800)

Unfortunately originally I did not add the location — this was growing in Arlington Virginia. I have added the location.
In response to the comments:
Even in Arlington, Virginia it has survived freezing temperatures.
I note that Arora indicates that Bondarzewia montana has round spores. As shown in Figures 7, 8 and 9, the spores of this specimen are oblong.
Arora indicates that the spores of Meripius giganteus are smooth. The spores of this specimen would not be described as smooth. See Figure 9
As to the host tree, I have added pictures of the tree.

By: Ruzica and Sava Krstic (ruzasava)
2013-12-30 00:13:56 PST (-0800)

This mushroom flew from East Coast where it was collected. Elmer, could you add the location data?


Cap appear to have
By: Daniel B. Wheeler (Tuberale)
2013-12-30 00:05:44 PST (-0800)

several sporocarps (caps) clustered in the hole. Would you agree with that statement, Oregon-learning? If the date the photo was taken is accurate (is it?) then the fungus has already survived one or more 20 degree days. Can that be possible without being a woody polypore?

Several quandries posed by photos.

Hello Elmer!
By: Danny Newman (myxomop)
2013-12-29 14:12:09 PST (-0800)

and welcome to Mushroom Observer! Sava showed me these collection of images of yours a few days ago. I thought it could be a Laetiporus of some sort, but the micro doesn’t match. Are you absolutely sure that these spores go with this fungus?

This is not maple.
By: Daniel B. Wheeler (Tuberale)
2013-12-29 13:01:06 PST (-0800)

The bark supports an identification of Sweet Gum as the host. The leaves are similar. Most Oregon maples have 5-7 (or more) lobes. Sweet Gum has 3-5 lobes.

This tree looks fairly old.

The pores of the fungus make it likely this is a Polyporales sensu lato.