Tuesday 11 June 2019

Agrocybe rivulosa - Wrinkled Field Cap Mushroom

Agrocybe rivulosa - Wrinkled Field Cap Mushroom

I found this lovely specimen at University Park, Nottingham where over the years have found many interesting and unusual mushrooms.  Behind the Boat House was a huge pile of bark chippings.  I always tend to investigate such 'piles' whether it be dung or chippings and there found a mushroom with a wrinkled cap. I'd not seen one quite like this.

On returning home I spent several hours searching for it in my various books and it did not feature.  After much searching on the internet I thought it might be Agrocybe rivulosa.  I sent some of my photographs to my friend Howard retired Recorder for Nottinghamshire Fungi Group and he confirmed it to be the case.

Thanks to M for driving me to the University Park in the rain so that I could get some more photographs.

Here is some background to this mushroom.

The first recorded sighting of this mushroom was in 2003 by a 
Dutch mycologist Marijke M. Nauta (source Wikipedia).  The first recording in the UK was in 2004.  It has since become quite common in Southern England due to the process of mulching flowerbeds which has caused its spreading. It is common in Holland, and mainland Europe. 

Also been recorded occasionally in Wales and Scotland.  Rivulosa refers to the wrinkled grooves like rivulets in the cap. Source First Nature.


The cap can reach a diameter of up to 10 cm.  The colour of the cap can vary from clay/yellow to pale orange-brown.  The gills are cream initially then turning grey.  The stem is fibrous and hollow, white turning pale ochre/grey with a large pendulous ring.  Chemical smell.  To been seen June - October on mulch and bark chippings.

Showing the wrinkled grooves in the cap.

Showing large pendulous ring.

Showing fibrous stem and base.

N.B. please note on the day the photographs were taken this mushroom was covered in small black insects.