Monday, October 31, 2016

Pulveroboletus ravenelii (Ravenel’s or Powdery Sulfur Bolete)

August-September, 2016. When I first spotted this mushroom, I was walking through a deeply shaded section in a mixed hardwood-pine woods. It stood out against its background.

It was a bright, ‘fluorescent’ yellow.

When I touched its stem, my fingers were covered with a yellow chalky substance. This bolete is covered with a bright yellow partial veil material when young; none remained on the cap of this specimen but it persisted on the stem.

The pore surface on young specimens was a bright yellow and bruised blue when damaged. The blue bruising observed with many boletes results when cells are damaged and a compound called boletol present in the cells is exposed to oxygen (oxidized) producing a color change from colorless to blue. (Interestingly, remnants of the veil are also visible at the margin of this cap.)

The pores on this bolete are relatively large - 2-3 pores/millimeter – round or angular in shape, and somewhat translucent in appearance.

In late September, I spotted a bolete with a duller yellow cap that had patches of orange. I thought it was a different species of bolete but, again when I touched it…

the yellow, chalky material, clearly visible in this photo, came off on my fingers. Immediately, I knew I had found an old specimen of Ravenel’s bolete.

The pore surface of this older specimen was a dark olive-gray that still bruised blue when damaged. 

During the period between late August and late September, I found Pulveroboletus ravenelii at three different locations along the trail between the beach and the fishing area. The combination of the bright yellow color and the presence of the yellow, chalky material were key characteristics in identifying this species. 

Pulveroboletus ravenelii is found in North and Central America, as well as in some Asian countries and Australia.

Related Post

Mushroom Expert: Pulveroboletus ravenelii 
Mykoweb: About Boletes
Discover Life: Pulveroboletus revenelii


Joy Window said...

Nice! I'll have to look out for this one. The Atlas of Living Australia website says it occurs in Australia. I've not seen it myself.

JSK said...

Interesting... It's interesting how some fungi are widely distributed and others are so geographically limited.
This one has only been reported from a couple of locations in Australia
If you find it, you'll have to document and submit a specimen to a herbarium.

Joy Window said...

I'll do that. Those two sightings on discoverlife are a long way apart, and in very different microclimates, so it must be in other places here. The Atlas of Living Australia has different sightings again. I wonder whether sightings on different websites ever get amalgmated. The photo at ALA shows a much thicker stem than yours.

From experience, Psilocybe cubensis also crushes blue - I wonder whether it's the same chemical causing it as in P. ravenelli.

JSK said...

I was fascinated by the sighting that looked like it was in SA, and in a dry area. The North Queensland observation didn't surprise me.
I hadn't seen the map in Atlas of Living Australia. Doesn't surprise me that there'd be a lot more sighting. It looks like it's much easier to submit observations.
It looks like Discover Life uses three resources: Mushroom Observer, Mycoweb, and a Taiwanese group. However there's no linkage from MO to DL for observations.
I usually submit my observations to Mushroom Observer; it's relatively easy.
It's possible to submit observations to DL, but involves downloading/installing software etc. Don't think any of the various groups amalgamate observations.
I noticed that the pic in ALA had a much thicker stem. All of 'mine' had relatively thin stems. The pic in DL also has thick stems.
It's been very dry here this year. Wonder if the stems would be thinker in a year with normal rainfall. We're in an el Nina cycle at the moment. If we ever get a year with normal rainfall, it'll be interesting to see what they look like.