Paxillus

[flaxton]

Cybershot posted a photo of Paxillus (involutus) on the Gallery a couple of days ago and I posted a photo of Paxillus rubicundulus yesterday and they both look very similar.





It was suggested that it might be a topic for the forum.

Paxillus involutus (actually part of the Bolete family - the gills will peel away from the cap easily) is the common species and it grows with both broad leaved trees and conifers and until relatively recently was thought to be edible. They have now found that it contains a poison which builds up in your system until
The methods of distinguishing it from its very close cousin rubicundulus (filimentosus is not now thought to be a separate species) are the depth of colour the gill change to when damaged (rubicundulus bruises to a paler and redder brown), rubicundulus only grows with alder and its spores are smaller than involutus.
Just to confuse the issue there is now a new kid on the block ammoniaviresens. This is almost identical to involutus but the cap(when the cuticle is peeled back) changes to green when a drop of ammonia is applied instead of the usual reaction which is a change to pink for involutus. It is also thought not to grow with birch.
As with an awful lot of identification a microscope is needed even if it is just to measure the size and shape of the spores.

Mal

[Leif]

Fascinating. I never knew there were several related species.

[cybershot]

Thanks for a well informed response to my commentary Mal. It serves to emphasize once more just how difficult it can be to identify and differentiate the species solely by comparison of macroscopic characteristics, especially when so closely related.

Many of us would like to be able to satisfy our curiosity by means of a photo placed on the forum but as you point out, in this respect, there many other indicators to note from a field study which would help those with the in-depth knowledge and experience to assist in our plight.

David

[PMG]

Originally Posted by flaxton

Cybershot posted a photo of Paxillus (involutus) on the Gallery a couple of days ago and I posted a photo of Paxillus rubicundulus yesterday and they both look very similar.





It was suggested that it might be a topic for the forum.

Paxillus involutus (actually part of the Bolete family - the gills will peel away from the cap easily) is the common species and it grows with both broad leaved trees and conifers and until relatively recently was thought to be edible. They have now found that it contains a poison which builds up in your system until
The methods of distinguishing it from its very close cousin rubicundulus (filimentosus is not now thought to be a separate species) are the depth of colour the gill change to when damaged (rubicundulus bruises to a paler and redder brown), rubicundulus only grows with alder and its spores are smaller than involutus.
Just to confuse the issue there is now a new kid on the block ammoniaviresens. This is almost identical to involutus but the cap(when the cuticle is peeled back) changes to green when a drop of ammonia is applied instead of the usual reaction which is a change to pink for involutus. It is also thought not to grow with birch.
As with an awful lot of identification a microscope is needed even if it is just to measure the size and shape of the spores.

Mal

They have now found that it contains a poison which builds up in your system until

I'm glad you've put this in Mal as I keep reading where folk are thinking they have an ID from a photo and it makes me shivver to think that someone might make a mistake and be, at the least, very ill - or even very dead quite often by kidney failure, out of the blue so to speak........

Pauline