Timebomb Toadstool – The Brown Roll-Rim

The words ‘Mushroom’ and ‘Toadstool’ are not truly scientific names, but general common usage describes these as edible or inedible (and poisonous) fungi respectively. But there is a grey area, (internationally speaking) regarding this mushroom or should I say toadstool?. It is still sold in eastern Europe markets, where-as here at home in the UK, it is strongly advised to be avoided. Over time, this fiendish toadstool can release it’s toxins and seriously poison you…

The Brown Roll-Rim (Paxillus involutus) is a very common toadstool found throughout the UK and Europe. I have come across it many times in mixed woodland. If picked for eating it can lose it’s toxicity once thoroughly cooked, but over time and if eaten on a regular basis, it’s toxin will enter the bloodstream and systematically cause the destruction of the red blood cells. Not very pleasant and definitely not worth the risk. There’s no real timescale for when and if this will happen, but I think it’s best described as a ticking time-bomb!

The common name helps describe this naughty toadstool quite well. Naturally a brown toadstool, it’s rim remains ‘inrolled’ although less so when expanded as it grows – see picture on the left – excuse long fingernails!). The texture when younger is finely felted and later becomes smooth (slimy when wet).

Size-wise, it can grow from 5 – 15cm in diametre when fully mature and has a distinct hazel brown colour (tawny brown / olive when younger) often dotted with darker orange/brown blotches.

The crowded, decurrent gills are a reliable feature for identification also. They ‘bruise’ dark brown on handling are easily separated from the cap flesh.

Being very common in broad leaved and sometimes coniferous woodland (even parks and gardens), you will most likely stumble across these toadstools during late summer to late autumn. They have been classed as deadly poisonous and therefore, to repeat myself again, just avoid them. Several deaths have been reported from Europe. Better the devil you know – to coin a phrase!

The Brown Roll-Rim Toadstool – Viscid when wet and brusing dark brown on the gills (top). Younger examples are more finely felted when young before becoming smoother.

PS. If you want to get scientific – check out this eco-news on the study of this very mushroom (and related species): http://www.jgi.doe.gov/sequencing/why/99182.html