Observation 108665: Hapalopilus croceus (Pers.) Donk

When: 2012-09-05

Collection location: Silver Spring, Montgomery Co., Maryland, USA [Click for map]

Who: John S. Harper (jsharper)

No specimen available

Two specimens found several miles apart in a 2 week period. (This observation is the most recent and larger of the two specimens collected.) Second observation is posted separately but noted here to indicate that unusual local conditions must have been favorable for this fruiting — I have never found this mushroom before during 7 years of very local collecting. Unusual weather comments: Hot early spring (lousy morel season), some rain end of June, dry very hot summer in early July for about 10 days, more normal rainfall in August. Everything seemed advanced about 2 weeks in appearance this year.

Both specimens were found on well-decayed log of indeterminate species.

Bright orange soft pore surface, dull orange brown (maybe “golden”) irregular lumpy pileus (not glabrous). Color and shape somewhat like a Pycnoporus but much larger, pores much larger. Firm but not conk-like. This specimen was 12″ × 15″ × 3″ thick. Odor not notable.

KOH on pileus, pores and context produce, over about a minute, a persistent purplish reaction. See photos of this and the related observation. On the pileus, I might call it reddish purple, but it seems more lilac on the context.

I could not initially identify this mushroom, but after a couple of suggestions on MO (thank you), I researched more online, and believe this is probably what is being called a Hapalopilus croceus (and perhaps several other names – see below). However, inconsistently, this specimen is nearly twice the size of the indicated range of size at 20 cm. wide This specimen was about 38 cm by 30 cm across, and 7.5 cm thick at the center.

Hapalopilus genus identification had been suggested to me by one of our club’s identifiers, noting that Noah Siegel had found a specimen in his recent visit to our club in early August. But it was not in any of my guides and the photo at http://mushroomobserver.org/name/show_name/19373 did not look similar. MO also comments under look-alikes for H. nidulans: “Hapalopilus croceus is much larger, up to 20.5 cm wide. It has a reddish orange pore surface but stains bright red in KOH, not purple.” [I would not call my stain reactions bright red at all.] Nor did it look like the photo at http://www.illinoismushrooms.com/Hapalopilus%20croceus.html. But a good description and photos matching mine were at http://www.messiah.edu/....

The messiah.edu posting also noted there that synonyms were Polyporus croceus Pers.: Fr.; and Aurantioporus croceus. It helpfully explains: "Hapalopilus means “with a soft, tender pileus or cap”; croceus means “saffron yellow” although specimens are bright orange when fresh."

See http://data.nbn.org.uk/... for indication that Hapalopilus croceus is a “badly formed name” and that another synonym is Boletus croceus.

Also see http://ar.mycobank.org/...

At this point, it appears there is some naming confusion here and I am giving up for the time being. Anyone who wants to sort this out more, you are welcome to comment to your heart’s content.

This seems to be an infrequently found mushroom. I will keep it in the refrigerator for a while and may prepare a herbarium specimen. If anyone wants a piece to look at, let me know.

Species Lists


Field photo
Field photo
KOH – purple-ish, not bright red
KOH – purple-ish, not bright red
KOH – purple-ish, not bright red

Proposed Names

-8% (2)
Recognized by sight
-9% (3)
Recognized by sight
86% (4)
Eye3 Eyes3
Recognized by sight: put a drop of KOH on it and report back

Please login to propose your own names and vote on existing names.

Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Truncated URLs are intentional
By: Nathan Wilson (nathan)
2012-09-10 18:14:08 PDT (-0700)

The links should still work. The problem is that URLs can be really long and they can mess up the formatting of the page if left in all their glory.

Lots of help from my friends
By: John S. Harper (jsharper)
2012-09-06 11:05:15 PDT (-0700)

After completing my more thorough write-up based on A. Virosa’s suggestion, I realized that it was Noah commenting, which led me to find more obscure info on the internet via google. Thanks Noah. (Mitch had remembered the genus you suggested, but not the species, on the foray in August).

I am noticing that the URL’s in my expanded notes are truncated. I am not sure why that is, but I will try to fix those up. The one that had the best photos and info were at http://www.messiah.edu/...

By: Danny Newman (myxomop)
2012-09-05 14:03:50 PDT (-0700)

two specimens found several miles apart in a 2 week period should be in two separate observations.

edit: if ever there were a model observation for the transformation from a buried, forgotten “Fungi sp.” to a detail-rich, insightful, thoroughly-documented and thereby quite identifiable observation, this would be it. Thank you, John.

Created: 2012-09-05 08:18:48 PDT (-0700)
Last modified: 2013-02-08 14:55:33 PST (-0800)
Viewed: 231 times, last viewed: 2018-06-14 13:38:18 PDT (-0700)
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