Observation 154252: Scleroderma polyrhizum (J.F. Gmel.) Pers.

Flesh turns wine red at edges when cut. Fruiting body 10.2 cm across. Found in mulch under birch. Cracks occur in top of cap where spores were expected to be released. Half buried in soil. First seen 2 weeks ago but only collected yesterday. No reaction to 5% KOH on cap or flesh. Photographed one day after collected, and thus it turned yellow. Initially thought to be white. Basal mycelium white. Smell: fungal (like Agaricus bisporus) when fresh. No smell when one day old. Spores (7) 8 (9) um on average (spores could have been immature). Lightly ornamented (like ‘A’ in mushroomexpert key. Globose.


view of top of left half
side view of left half
inside of left half
side view of right half
top view of right half
inside of right half

Proposed Names

24% (2)
Recognized by sight
Used references: Kuo’s Scleroderma key at MushroomExpert.com. BTW, this is very large for a Scleroderma!
55% (1)
Eye3 Eyes3
Recognized by sight: Fruiting body in 9-13 cm range. Turns wine red at edges when cut (not seen in 1 day old photographs)
Based on microscopic features: Spores in 5-10um range.
Based on chemical features: Negative in KOH.

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

Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
I agree it’s possible.
By: Daniel B. Wheeler (Tuberale)
2013-12-08 10:56:07 PST (-0800)
By: Drew Parker (mycotrope)
2013-12-07 20:50:39 PST (-0800)

To me the gleba looks rather dark purplish-gray-brown with a partially blackish margin. I think that would be in the ballpark. And at 9-13 cm, I doubt that it’s a baby. Anyway, my point is S. polyrhizum seems a better fit than S. hypogaeum.

By: Daniel B. Wheeler (Tuberale)
2013-12-07 18:46:34 PST (-0800)

the gleba appears a mixture of sterile tissue and spore-bearing gleba.

In addition, obs. varies from description in MatchMaker in (not) “surrounded by a thin cottony layer, part of the peridium,” and “soon dark gray to purple-black or black”. This is not an old specimen. It is young. Where is there any hint of purple-black or black?

By: Drew Parker (mycotrope)
2013-12-07 13:09:56 PST (-0800)

What about the gleba (I don’t think you meant “sterile areas” since that is the spore mass)in this observation is atypical of S. polyrhizum? The following from MatchMaker.

“Spore Mass: compact to powdery; gray-brown; with whitish and yellowish filaments; when young shows alveolar structure and is surrounded by a thin cottony layer, part of the peridium, which is lost with opening of the fruitbody, (Guzman), “firm when young, becoming powdery, brown to purplish brown, becoming blackish brown at maturity”, (Bessette), dark brown (McKnight, Ramsey), “at first firm and pallid, soon dark gray to purple-black or black (and still firm), eventually becoming brown to dark brown or purple-brown and powdery”, (Arora)"

Also “usually not with trees”, as you know, doesn’t mean always not with trees.

By: Daniel B. Wheeler (Tuberale)
2013-12-07 11:49:04 PST (-0800)

a couple of features don’t. Found with birch indicates mycorrhizal relationship. S. polyrhizum, according to Kuo, usually not with trees or in wooded environment, but in “meadows”.

Features of the gleba: those large solid sterile areas. Not typical of S. polyrhizum.

I have found what was identified as S. polyrhizum in sand dunes near Tillamook, Oregon. These were indeed the largest Scleroderma I have found to date. They were also conspicuously caespitose, or clustered. While individual specimens were to 10cm, the entire mass was much larger, including 10-15 specimens fruiting together. They were also mostly epigeous, with very little “underground”. I rather questioned the identification due to large rhizomorphs on the base, nearly forming a sterile base. But collecting that would have requires a shovel or larger.

That collection was found in full-canopy Lodgepole pine, Monterey cypress and Douglas-fir. Perhaps S. polyrhizum is associated full canopy woodlands more than is given credit for.

Several features…
By: Drew Parker (mycotrope)
2013-12-06 17:12:23 PST (-0800)

Clearly favor S. polyrhizum over S. hypogaeum. These include size of fruitbody, spore size, shape, and ornamentation, and habitat. S. hypogaeum is known from conifer forests in the western US, whereas S. polyrhizum is typically found in the open or with hardwoods, and is more widespread.

Thank you for your opinion
By: Emma Harrower (eharrower)
2013-12-06 16:21:58 PST (-0800)

I am convinced that this is a Scleroderma. I never eat anything that I cannot identify and I never eat anything that someone I personally know has not identified as edible. I am aware that the dark spores mean it is past it’s edibility date, if it were an edible species like Calvatia. My prime interest is in biodiversity and the culinary aspect came later when people started feeding me wild mushrooms.

Fruiting “bodies” not fused.
By: Daniel B. Wheeler (Tuberale)
2013-12-05 12:42:08 PST (-0800)

Had that been the case, there would be clear reference to it on the peridium: deep grooves.

Dense gleba, white veins and purple to black gleba also are characteristics of S. cepa. Peridium can be thick, but not the extreme thickness shown here. “…with a sterile base that often is projected as a stem.”- according to NATS Field Guide To Selected North American Truffles and Truffle-like Fungi. Same source says “slowly staining pink where cut”. Spores “7-12 microns, globose, dark brown, spiny.” The photo which accompanies this description shows a peridium of 2-3 mm. I would say parts of your observation are closer to 2cm thick.

There appear to be several other Sclerodermas which do not key out in Kuo. (Not his fault.)

The only thing I hope to convince you of, Emma, is that this is Scleroderma. All Sclerodermas must be considered poisonous until proven otherwise. I hope you don’t consider testing on yourself, as past NATS co-presidents Dennis and Norene Wedam unintentionally did. They recovered. A 110-pound pot-bellied pig in Vancouver, Washington died after eating an unknown number of Sclerodermas in his backyard.

not totally convinced
By: Emma Harrower (eharrower)
2013-12-04 20:05:01 PST (-0800)

I will have to measure the spores again and see what the KOH reaction is again. If two fruiting bodies grew next to each other and fused, that could make a big fruiting body. I left one other specimen in the ground. The outer rind was very tough.

The extremely thick peridium
By: Daniel B. Wheeler (Tuberale)
2013-12-04 17:08:03 PST (-0800)

gives this one away; Scleroderma hypogaeum. Scleroderma cepa peridium is typically 2-3mm thick. This obs. has extremely thick peridium, and very thick interior sterile tissue. Also, S. cepa is extremely hard and often bounced like a superball.

Created: 2013-12-04 15:31:11 PST (-0800)
Last modified: 2013-12-06 17:13:48 PST (-0800)
Viewed: 137 times, last viewed: 2018-08-27 08:00:27 PDT (-0700)
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