Observation 28562: Cystolepiota petasiformis (Murrill) Vellinga

When: 2009-11-19

Collection location: Mill Valley, California, USA [Click for map]

Who: Erin Page Blanchard (CureCat)

Specimen available

3.5 – 5 cm

These were really interesting. They remind me of the Cystolepiota that Inski finds .

A few odd things… First, the colour. These were not white, they are a pink/buff colour, and I can not tell if this is discolouration due to aging or drying, though it seems pretty widespread, so I am going to guess probably not, even though I have seen apparent reddish darkening from other Cystolepiota due to handling.. Also notice the red spots on the lamelle? I have no idea what is up with that, but when I picked them some red liquid from those spots on the lamelle got onto my hand, and it was very red. The most bizarre feature is the gill attachment, it is very distinctive!

These were found growing under some bushes in someones front yard. The soil they grew from was well saturated from the sprinklers, and seemed to have a lot of clay, and very little leaf debris.

I am not positive these are Cystolepiota but I don’t know what else they might be. Cystoderma came to mind, but the granules of these are too powdery.

Proposed Names

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
By: Erin Page Blanchard (CureCat)
2009-11-23 20:01:51 CST (-0500)

Thank you both for sharing your opinion.

Uh, compared with numerous other species I have found images of, these look nothing like the two confirmed collections of C. petasiformis that I linked to.
After reading the description, it sounded like the fluff was right for that species, but now having seen pictures of confirmed collections and especially realizing that I found one of them, I don’t think the fluff is similar at all. So unless it is macroscopically very variable with the species, I cannot imagine that they are the same. I remember collecting that one from 2 years ago, and I could hardly pick it without the fluff falling off all over the place. And it was WAY more powdery, and not patchy and erect like this collection. I was also able to handle these without the fluff coming off.
Furthermore, they were that colour when I found them, and did not seem to change colour over time. Where as the other collection was snow white when I picked it, and darkened over the course of a day or two.

But I guess microscopy will have to determine the identity.

I am a little bit surprised that I have not found any good photos of similar gill attachment.

These two photos are not as detailed, but look like they might have something similar going on….



By: Johannes Harnisch (Johann Harnisch)
2009-11-23 19:31:40 CST (-0500)
By: Michael W (Michael Wallace)
2009-11-23 19:22:44 CST (-0500)

I think Else uses the term velum for the oblong and occasionally subglobose cells covering the basidiocarps of this species, there is also a lack of pleurocystidia and cheilocystidia.

Now that the season is over here in NZ I should start photographing the micro characters of the many collections I’ve made!

By: Joshua Birkebak (Shua)
2009-11-23 18:14:05 CST (-0500)

Unfortunately the spore ornamentation is hard to see even under 1000×... but the lack of clamps and the elongate as opposed to globose fluff. (yes, that is the technical term for them…)

By: Michael W (Michael Wallace)
2009-11-23 15:54:30 CST (-0500)

It will be interesting to see the ornamentation of the spores and to confirm the lack of clamp connections in this collection!

By: Joshua Birkebak (Shua)
2009-11-23 12:25:45 CST (-0500)

That looks alot like petasiformis to me! This is an older specimen that has somewhat discolored but hasn’t had most of its super powdery covering off Like the other observation you linked to… It was originally described with a conical powdery covering like seen in your photos.

C. pulverulenta is probably a european synonym for petasiformis from Seattle and all along the western coast. It is also notorious for discoloring reddish or cinnamon.

Just talking to myself…
By: Erin Page Blanchard (CureCat)
2009-11-23 01:25:30 CST (-0500)

I am basically just posting as I find more information or get new ideas…

Anyway, right now I am having a hard time finding any photos of Cystolepiota with this sort of gill attachment. A number of species resemble this one, especially noting the semi-erect granulose patches on the pileus, with a more dense concentration near the apex. But so far all of the photos of the gill attachment for those seemingly similar species are typical free attachment.

Here are some strikingly similar photos of C. pulverulenta, but I can’t see the attachment!!!



I should probably just ask Else, I bet she would know in a second. But this is kind of fun.

Ahh crap
By: Erin Page Blanchard (CureCat)
2009-11-22 22:29:33 CST (-0500)

One problem… I have found C. petasiformis before (I just did not remember it being identified to species) and it looks nothing like this. Damn. And for a second there I thought this would be easy.

Here is observation 4858, the real C. petasiformis, that I found two years ago, and interestingly, only a hundred or so meters from the location that I found this collection.

You can see that the collection from 2 years ago that Else identified matches very well with the photo of C. petasiformis seen in this Cystolepiota of California key.


C. petasiformis
By: Erin Page Blanchard (CureCat)
2009-11-22 21:57:40 CST (-0500)

After reading the Mycotaxon article, which includes the macroscopic description of the species, I think you are spot on Inski.

Among the material studied in the article, 3 collections are from Northern California. A collection of C. petasiformis was made in San Mateo County, Humboldt County, and in Marin County (the city of Mill Valley, where my collections was made, is in Marin County), specifically Bear Valley Trail in Pt. Reyes. So all of this sounds very reasonable for C. petasiformis.


By: Erin Page Blanchard (CureCat)
2009-11-21 03:08:08 CST (-0500)

Did you read the notes? :-P

Hehehe, it was growing under some shrubs or bushes of some kind, in Mill Valley. I do not know whether the plants are native or not. The ground was really wet, almost soggy, and the soil seemed to have a lot of clay and pebbles, but very little leafy debris on top.

By: Douglas Smith (douglas)
2009-11-21 02:32:55 CST (-0500)

Where did you find that one? Wow, look at that, neat! My vote would be more for Cystolepiota, that looks more like it should be coming from New Zealand or some such than California…

Created: 2009-11-20 21:55:50 CST (-0500)
Last modified: 2009-11-20 21:55:50 CST (-0500)
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