Observation 202110: Rhizopogon Fr. & Nordholm

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Spore size as described
By: Daniel B. Wheeler (Tuberale)
2015-04-02 11:31:07 PDT (-0700)

certainly matches Rhizopogon. Trappea I would not consider since the gleba has no green nor gelatinous columella; and the spores in Trappea are much smaller than any Rhizopogons. Hymenogaster would normally produce an obnoxious aroma at maturity, and lacks surface rhizomorphs on the peridium.

You’re doing good so far, George. Can you imagine what Alexander H. Smith must have thought when he discovered these rather common spore bundles, and tried to key them out? No wonder one of the first keys had 500+ species! Alex may have had it slightly easier though, with that trick microscopic eye of his. He could often see spore size, shape and overall appearance just by ‘eyeballing’ it.

That said, I bet sometime in the future this will become another subset of Rhizopogon, based on the very few locules present.

Photo of spores … missing
By: George Riner (mycogeo)
2015-04-02 08:38:26 PDT (-0700)

I have tried to produce a photo of the spores through a microscope, but have been unsuccessful so far. But I can comment on what I see in the scope compared to what I read in “Field Guide to North American Truffles”, Trappe, et al. What I see are oblong colorless undecorated and without interior features. The Hymenogaster on p. 52 show brown spores that are rather angular in shape. The Trappea on p. 96 appear similar to this collection – although the small photo of spores shows seems to show some contrast or darkening, perhaps a contrast or a staining reaction?. The spores of this collection are in the 4-5 × 6-8 µ size.

Numerous red-staining thread-like rhizomorphs present on peridium,
By: Daniel B. Wheeler (Tuberale)
2015-04-01 10:38:33 PDT (-0700)

making Rhizopogon possible if not likely. My problem with identification of Rhizopogon in in the gleba (interior), which may not be much of a problem at all.

The gleba is slightly loculate, which may place this species in Rhizopogon. But there are very few locules present, even at maximum magnification. I have to admit I have not looked at that many Rhizopogons (only 1,000 or so). Most have much larger locules, many visible with the naked eye. OTOH, Rhizopogon has gone through many revisions since Smith first suggested the genus.

Again, while I am certainly not an expert in Rhizopogon, I think we must consider this a Rhizopogon, rather than Hymenogaster or Trappea, at least as those genus are currently identified.

Created: 2015-03-31 08:35:43 PDT (-0700)
Last modified: 2015-04-01 10:38:49 PDT (-0700)
Viewed: 37 times, last viewed: 2016-03-09 21:24:32 PST (-0800)
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