Observation 107010: Rhizopogon subcaerulescens group

When: 2012-08-24

Collection location: Echo Summit, El Dorado Co., California, USA [Click for map]


Who: Mike McCurdy (lesmcurdy)

Specimen available

This was found approximately 12" from the location as the truffle in MO observation 105878, attempting to find another of that truffle, (whatever it turns out to be). This appears to be a false truffle resembling the Mushrooms Demystified description of Hymenogaster sublilacinus which indicates that it is common in the Sierra Nevada, found with conifers, specifically lodgepole pine, which was the primary tree in this location. This specimen was 3.8 cm in diameter. No microscopy has been done, but the material is available. The odor and flavor are both reminiscent of the odor and flavor of raw Boletus edulils.

Proposed Names

0% (2)
Recognized by sight
61% (2)
Recognized by sight: confirmed by Michael Castellano (see his comments below).

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Eye3 = Observer’s choice
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confirmed Rhizopogon subcaerulescens group
By: Michael Castellano (trufflercaz)
2012-10-11 12:03:10 CDT (-0400)


Interesting Rhizopogon species not typical of ones in the subcearulescens group as the peridium is a bit unusual, at least to me.

nice find.


Herbarium number 35964

Thank you.
By: Mike McCurdy (lesmcurdy)
2012-09-10 23:26:07 CDT (-0400)

The material will be on its way tomorrow. Once you have the chance to examine it, please up date the name.

looks like
By: Michael Castellano (trufflercaz)
2012-09-10 11:38:00 CDT (-0400)

Rhizopogon subcaerulescens complex.

send a sample for confirmation

By: Daniel B. Wheeler (Tuberale)
2012-08-28 10:44:50 CDT (-0400)

The more you pay attention to the upper 6 inches of soil, the more life that is found. And often it is unexpected by most people. Biologically the humus layer and upper soil surface may be the most diverse area on Earth. I spoke to a soil scientist from Oregon State University regarding soils 20 years ago. He told me he had found 20,000 new species … in one day! Just by looking at a single square foot of soil from the H J Andrews Experimental Forest near Eugene, Oregon. In that single square foot, he discovered a teeming millieu of soil-inhabitating arthropods, spiders, scorpions, pseudoscorpions, centipedes, millipedes, etc; everything eating and recycling the humus on the ground, or the feces produced from those degraders, or preying on them. Where else can someone find 20,000 new species in a single day … except right under your feet?

Thank you
By: Mike McCurdy (lesmcurdy)
2012-08-28 02:42:06 CDT (-0400)

for the input. Lots of good information, but there are always more questions than answers on the way to understanding these things, especially when dealing only with photos. Microscopy would help, but no microscope here. I do have the material if anyone is interested. Sounds like this is probably a common, conifer loving critter, and I appreciate that it gave life to an otherwise fruitless attempt to find something else.

Just enlarged the last photo to maximum size.
By: Daniel B. Wheeler (Tuberale)
2012-08-28 02:39:06 CDT (-0400)

There are locules present. They are tiny. If the sporocarp is 3.8cm in diameter at the widest as stated, then locules are 1mm or less in diameter. Sorry I missed them earlier. Photo MUST be enlarged to maximum, and examined with a magnifying glass for me to see them, although some are nearly circular in shape.

This is not a typical Rhizopogon, which generally has much larger locules. Nor is it a “typical” Hymenogaster, which would have a columella visible in cross-section. Hysterangium “normally” also has a columella, usually cartilaginous or a differently colored sterile structure. Using Smith, Smith & Weber as key, necessary first to have microscopy and spore size to determine approximate grouping of fungi. Let’s go with basidiomycete to begin with, as I know of no ascomycete or zygomycete that has locules.

In Smith, Smith & Weber, p. 295 under Rhizopogon salebrosus
By: Daniel B. Wheeler (Tuberale)
2012-08-28 02:27:33 CDT (-0400)

“Fruiting body 1-3 cm, yellow-brown to cinnamon-brown with an overlay of vinaceous-brown rhizomorphs, FeSO4 dark olive on the cutis; KOH on cut peridial surface vinaceous; spores 7-9 (10) X 2.8-3.5 (4) microns; inflated cells present in the peridium as cut ends of cells.
“Under fir and pine, central Idaho, August.”

Also in Smith, Smith & Weber Zelleromyces is described as typically with a well-defined columella. I see no columella here. Nor do I see any large locules. The lack of these two features drastically cuts down what this obs. might be. I’m afraid the only way to solve the dilemma is through spore identification and some chemical characteristics. For that, the herbarium specimen is required. I would suggest sending your photos first to Matt Trappe via email. I do not have his current email address, although it might be available at the NATS website. Wait to send the dried sporocarp until after Matt asks for it.

Your description of “very cohesive and rubbery” sounds a lot like Hysterangium. Most Hysterangium are noted for having well-defined columellas, often with transluscent columellas. Smith, Smith & Weber describes the Hysterangiaceae with “gleba firm to tough and gelatinous at first becoming slimy to mucilaginous and foul-smelling at maturity…” I wouldn’t call Hysterangium foul-smelling; perhaps this is a reference to the Phallogaster and Clathraceae, which are related. Mature Hysterangium separabile has an odor quite similar to over-ripe olives, but with a solid gleba that becomes brittle and slightly less rubbery in extreme age.

Sorry this doesn’t solve the question of what this is. Hope it helps somewhat.

The sporocarp,
By: Mike McCurdy (lesmcurdy)
2012-08-28 00:35:32 CDT (-0400)

when sliced was very cohesive and rubbery. Cutting it left a smooth surface, not crumbly at all. It was not nearly as soft as a cooked potato.

I’ve added 2 photos. The one in my hand is not good quality, but within moments of coming out of the ground. The second may show some of the “fuzziness” you mentioned.

Just enlarged the second photo to largest size.
By: Daniel B. Wheeler (Tuberale)
2012-08-28 00:16:31 CDT (-0400)

I can see a single, solitary larger chamber on the left-hand side of the sporocarp. And the blue reaction visible in the first photo has toned down considerably in the second photo. Plus the gleba has apparently darkened or matured – or may both. The locules I expected to find were almost not present, suggesting they are tiny. And associated with Pinus.

I’m was going to suggest Cystangium here. Then thought better of it. I don’t see the rhizomorphs which should be present on most forms of Rhizopogon (and often on Hymenogaster too). The bluing of the peridium has me, uh, confused. And Cystangium (formerly mostly Martellia) usually don’t get this dark – ever as far as I know.

Do you remember what the texture of the sporocarp was when sliced? Was it soft like a marshmallow or cooked potato? (If so, then may still be the flavor du jour of Cystangium (formerly Martellia) or whatever it is currently called.) If harder and perhaps with a slight latex/tackiness to cut gleba, could be Zelleromyces.

Learning to use the camera
By: Mike McCurdy (lesmcurdy)
2012-08-28 00:14:48 CDT (-0400)

effectively is a work in progress. These photos were taken within moments of one another in different light. I’ll look through the rest of the photos to see if one might be better. Thank you for the input.

By enlarging the first photo to “huge”
By: Daniel B. Wheeler (Tuberale)
2012-08-28 00:00:41 CDT (-0400)

I can see some fuzz on the peridium, as well as a bluing reaction to the cut peridium. The lack of a glue or library-paste odor probably eliminates Hymenogaster sublilacinus. Probably. But I have not collected in your area.

Was the second photo
By: Daniel B. Wheeler (Tuberale)
2012-08-27 23:55:24 CDT (-0400)

taken some time later? How much later?

FYI, should you find truffle-like fungi in the future, a close-up (as close as possible) of the gleba and at least a portion of peridium is helpful.

With such a photo, it should be simple to determine whether this is a Rhizopogon or Hymenogaster: Hymenogaster has a vestigial columella within the gleba, which would show up as thicker sterile veins similar to the trunk and branches of a tree. Rhizopogon should have fuzzy peridium (outer covering) which may or may not be composed of very fine hair-like fuzz, which sometimes stains a different color.

Created: 2012-08-26 03:13:21 CDT (-0400)
Last modified: 2012-10-11 13:03:21 CDT (-0400)
Viewed: 283 times, last viewed: 2018-03-13 00:41:50 CDT (-0400)
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