Observation 49496: Pleurotus dryinus (Pers.) P. Kumm.

When: 1999-06-27

Collection location: Wildcat Mountain State Park, Vernon Co., Wisconsin, USA [Click for map]

Who: Steve Nelsen (sfnelsen)

No specimen available

See my comment on 49489, the reason for this posting
On a trip to Wildcat Mountain State Park on June 27th 1999, we found several specimens of a whitish, veiled pleurotoid fungus that had a distinctly yellowish cap under a white veil that was growing on a log (probably maple) still covered with hard bark. I contacted Hal Burdsall, who was still at Forest Products in Madison then, and he told me there are no yellow tones, ever, in P. dryinus. I then showed him the specimens, which he said were conclusively not P. dryinus, but he did not recognize it. They were too young for spores, and I had dried them all anyway (which kills the the spores, making it impossible to culture them), so the next week-end we returned the 100 miles north-west of Madison to Wildcat Mountain to get some for culturing. The log they were on was near the trail, and only a few hundred yards off the parking lot, so I expected to find it again. Luckily, no one had destroyed the ones I had left, and they were indeed there. In only six days the appearence of this mushroom had changed more than almost any I have ever seen. It had become very much larger, was now densely covered with hairs on the cap and especially the stem (noted as characteristic of Panus strigosus Berkeley and Curtis and by Peck, for specimens found in 1872 and repeated verbatum by McElvaine in 1902), and become much yellower. All traces of the veil apparent in the buttons were gone. Although it is not one of the most-covered species, the specimens first found on June 27th were now easily recognizable as P. strigosus from the more extensive descriptions and illustrations of this species in Kauffman (1918), O. K. Miller (1977), Smith, Smith, and Weber (1979), and Phillips (1991). I recognized it immediately because it is very distinctive, and I had seen it previously in three different years at Baxter’s Hollow as well as at Devils Lake and in the Smoky Mountains. Most surprisingly, however, P. strigosus was absent from the extensive species list of for the Smoky Mountains. I think it is clear that none of the above authors could ever have seen buttons of “Panus strigosus”; they are quite unrecognizable from the descriptions given. However, I think what has happened is clear. There is a second, related species, Panus levis B. & C. (originally spelled lævis using a diphthong, later not, and the spelling has often been “modernized” to levis, as in IF), that is less commonly described. I wasn’t thinking of it at all, because my edition of Hard (1908, 1976 Dover reprint) has updated nomenclature (by Gilliam in 1975), noting that Singer moved P. laevis to Pleurotus. This unfortunately put them in different genera in my order, and I never connected the two. This difficulty was only slightly less than finding them in Kauffman’s book, where the Panus key starts on p. 44 and Pleurotus key on p. 658. in the other volume. Nevertheless, Kauffman notes that strigosus and laevis are rather close (although he only describes laevis with 23 words in a key entry; he never thought that he saw it) and that strigosus is hard to tell from a Pleurotus. McIlvaine also clearly says that the two species are related, and Singer, who transferred both to Pleurotus, notes that the two species may be the same, which I think is the solution. Hessler (Mushrooms of the Great Smokies, 1960, reprint 1975) includes only Panus levis, and is the only one to state clearly that it has a veil when young (Peck, Hard, Kauffman and McIlvaine all use various other comments instead of calling it a veil). This explains to my satisfaction why strigosus does not appear in the Smokey Mountains list; Hessler knows they are the same but doesn’t bother to tell you, and uses Pleurotus (B. & C.)Singer, synonym Panus B. & C. as its name in the Smoky Mountain list. Comparing the descriptions when both species are included, laevis is smoother (under the “matted hairs”), less than half the size, and whiter. I think the conclusion is unavoidable that Berkeley and Curtis came up with two names for the same species, laevis for young ones, and strigosus for mature ones. That has certainly happened a lot.
So if 49489 is not this stuff, and I cannot believe that it is, what is it?


One week after the first pictures, same log. Huge change in appearance
Taken at Henwallow Hollow, GSMNP. This clearly shows the long hairs on the stem.

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Add Comment
Excellent info!
By: Jon Shaffer (watchcat)
2017-04-21 23:00:14 CEST (+0200)
levis and dryinus
By: Britt Bunyard (Fungi magazine) (bbunyard)
2010-09-28 21:45:35 CEST (+0200)

I, too, have long been puzzled by levis and dryinus (as well as trying to keep track of whether it was Panus, Pleurotus, Lentinus, et al.). Just a couple of my own notes: We always see it on our Wisc Myco Soc Northwoods foray way up north near the Michigan border; saw it this year. We always see it mid July. I used to see it annually on a tree in Ohio. In all cases it was emerging from a wound on a maple tree. It looks to be the case in one of Steve Nelsen’s photos on MO. And I have read this somewhere in a fieldguide book. Ron, can you comment on this?

By: walt sturgeon (Mycowalt)
2010-08-11 01:21:06 CEST (+0200)

It may or not be noteworthy that both have a citrus odor. I have never seen a veil on Lentinus levis but it may be evanescent. The frosted cap of Pleurotus dryinus has been a macroscopic feature that I have always used along with the veil.

Petersen’s reply to query about levis and dryinus
By: Steve Nelsen (sfnelsen)
2010-08-10 20:55:28 CEST (+0200)

Steve -
You have stepped into a somewhat difficult taxonomic and nomenclatural swamp. Here is what I know (some from our own publications, others from dissertations by former students, etc.).
1. Pleurotus versus Panus:
A. Pleurotus never has true skeletal hyphae; Panus always has skeletal hyphae.
B. Panus was thought of as a subgenus of Lentinus by Pegler (the person who monographed worldwide Lentinus). Lentinus also has skeletal hyphae, of a different type than Panus. DNA studies tell us that Panus and Lentinus are separate at generic rank, but both genera belong to a group called the Polyporales or Aphyllophorales, an order parallel to the Agaricales (and therefore not agarics).
C. Panus “rudis” has long been considered a common (especially spring) fungus on wood. Studies of type specimens show that Panus “rudis” has an earlier name, Agaricus lecomtei, which has been properly transferred as Panus lecomtei (or Lentinus lecomtei, if you prefer). (My note: Index Fungorum does not make Agaricus lecomtei a synonym of Panus rudis), for which they list Lentinus strigosus as the “current name)

Summary: Taxonomically, Panus lecomtei has nothing to do with Pleurotus.

2. Pleurotus levis versus Pleurotus dryinus:
A. Pleurotus dryinus is separate from P. levis.
1) Isolates of the two species are not sexually compatible
2) Cultures of P. dryinus invariably produce lots of brown asexual spores; cultures of P. levis produce none.
3) Fruitbodies of both species turn yellowish (then yellow) in old age in the field, and fruitbodies of both species turn yellow on the drier. (so Burdsall was wrong on this point)
4) Fruitbodies of both species show an evanescent veil in youth, but that of P. dryinus is more persistent. (So Roody was wrong about Pl. levis having no veil; it is, however, hard to find.)
5) Pleurotus levis tends to be a warm-climate fungus – we get it here; I have collected it in Arkansas, Puerto Rico and Costa Rica. P. dryinus is a cool/cold weather fungus. I have collected it in Alaska, Washington (state), Scandinavia and northern Russia.
6) DNA studies confirm that the two are separate.
7) FYI, they are not the only species with a veil. P. calyptratus has a persistent veil, but fruitbodies are very different from those of P. dryinus or P. levis; virtually no stem – looks like a white-spored Crepidotus.
8) FYI, To my knowledge, P. levis is a New World species, but P. dryinus seems to be circum-boreal.

Summary: 100 miles north of Madison; my guess is that you have P. dryinus. June is an unusual time for it, but it may still be chilly up your way.

No one knows (anymore) why the fungus was named as Agaricus laevis (“laevis” means smooth). It is likely that the strigose cap surface is detersile, and when the strigosity is weathered away, the type specimen was either matted down or had become smooth. Nonetheless, P. levis and P. strigosus are synonyms, with A (=P) levis being the older name. (My note: Index Fungorum has Lentinus strigosus as the “current name” for Panus rudis, which means that they have it in a different Order than Pleurotus. They also have Lentinus levis as the “current name” for Pleurotus levis, so it is also in a different Order than Pleurotus. You would think (and hope) that fungi in different Orders would be easier to tell apart than that!)

All this may be more than you want, but you can use it as you wish.

Best regards. Ron Petersen
Petersen’s key to Pleurotus and descriptions of levis and dryinus, which make it clear that they are hard to tell apart, are linked on Michael Kuo’s website. I would link them here, but I do not know how.

Created: 2010-08-02 21:18:14 CEST (+0200)
Last modified: 2017-04-21 23:12:52 CEST (+0200)
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