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Vermonter

Pleurotus survey - oyster aficionados wanted

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Here are photos of two finds in Vermont this year. I like to think they are different species, pulmonarius and ostreatus, to explain their drastic differences. The white ones: September 21, maple tree, weather still fairly summery. The brown ones: November 9, log of uncertain variety, weather cold for autumn. I feel confident that the brown are ostreatus, but I believe many would consider these both ostreatus, and attribute the differences to environmental factors. What do you think: different species or the same? Or different subspecies?

pulmonarius1.jpg

pulmonarius2.jpg

pulmonarius3.jpg

ostreatus1.jpg

ostreatus2.jpg

ostreatus3.jpg

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They are definitely two different species in my opinion.  Here's what Mushroom Expert says on the subject:

 

"The separation of Pleurotus pulmonarius from the better-known, "true" oyster mushroom, Pleurotus ostreatus, is based on very good evidence that covers the three "species concepts" most commonly applied to fungi. In the laboratory, Pleurotus pulmonarius cannot "mate" with the other species in the oyster complex, so it is a good biological species. It also represents a fairly distinct morphological species, since it is paler (and frequently smaller) than the brownish Pleurotus ostreatus and appears to develop more of a stem, more of the time. DNA evidence supports Pleurotus pulmonarius as a phylogenetic species and, to top it all off, there is an ecological difference: it appears in warmer weather, appearing from late April through September, while Pleurotus ostreatus favors cold-weather conditions and appears from October through early April."

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Thanks for your input Steve B!  I think the white ones are a good fit for P. pulmonarius also.  However, when I first posted pictures of them on a local facebook group, a member with a good deal of experience believed them to be P. ostreatus.  That's why I'm looking for more opinions.

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I'd call the white ones "pulmonarius" and the gray ones "ostreatus". IMO the late-season ostreatus with the gray/tan/brown caps are the best edible type in the genus. One way to distinguish is by spore print color. Pulmonarius (and also P. populinus) have white spore print. Ostreatus has a pale smoky gray faintly lilac-tinged spore print. 

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Thanks a lot for your input, Dave W!  I didn't bother with spore prints, because I had read that the various Pleurotus species have the same range of colors: white-yellow-gray-lilac.  Mushroomexpert.com for example has "whitish, grayish, or lilac" for P. pulmonarius and "white to faintly yellowish, or lilac" for P. ostreatus.  However, other sources name other overlapping combinations within that range.  I'm interested to hear that you have noticed a clear distinction.

I really enjoyed the flavors and textures of both of these finds.  I harvested some of the late season ones after they had frozen solid, and found them to taste sweeter than before freezing.  But the Pleurotus I found most delicious this year were ones I believe to be P. dryinus (posted here)--surprisingly, because they don't have a great reputation as an edible.

 

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P. dryinus does have a nice flavor. I think some people tend to give it a low rating because the flesh can be a bit tough/chewy, especially near the stem. 

In my experience, the "summer Oysters" --P. pulmonarius-- have white spores, and the early/late P. ostreatus have the smoky-lilac spores. Mushroom Expert says the spores for P. populinus are always white. Also, P. populinus has larger spores (when viewed under a scope), but ostreatus and pulmonarius have spores with very similar measurements. I suppose that pale versions of ostreatus may be easily confused with pulmonarius. Perhaps my cap color-scheme suggestion is an oversimplification. But, in my experience, pulmonarius --which is usually smaller and with thinner flesh than ostreatus-- is always (almost) pure white. also, as Mushroom Expert says, pulmonarius often features a well-formed stem, sometimes almost centrally attached to the cap which gives some of the mushrooms an appearance that's seemingly unusual for an Oyster Mushroom. 

Of course, this is all basically academic, as Oyster Mushrooms are all good edibles. I bring some home whenever I find them. But, one related concern is the similarity of Pleurocybella porrigens (Angel Wings) to Pleurotus. P. porrigens grows on coniferous wood, as opposed to Pleurotus which is always found on wood of deciduous trees. There have been a few disturbing incidents regarding the consumption of P. porrigens. In Japan, some older people with pre-existing conditions associated with liver function became quite ill after consuming P. porrigens. I am now told that there have been more than one such incident, and that a toxin has been isolated out of P. porrigens. The specific illness suffered by victims affects the brain. Thus, the implication is that the toxin may affect a person whose liver does not function well enough to filter out the toxin before it finds its way through the bloodstream to the brain. I find this species on hemlock wood. I saw quite a bit this past fall. I used to collect it for the table, but I no longer consume it. Generally, thinner-fleshed than Pleurotus, but it does look fairly similar to white Oyster Mushrooms. Spore morphology immediately distinguishes Pleurocybella from Pleurotus.

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Thanks a lot Dave W!  I was initially concerned about the possibility of Pleurocybella porrigens with the white ones, but then learned that the maple tree ruled that out.  I read about the illnesses and deaths attributed to P. porrigens and definitely plan to avoid them, even though I know some people continue to eat them.

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