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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…

Brown roll-rimThe 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 and the margin may become very wavy.

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!

Note: See comments boxes below. To eat or not to eat! I know I won’t be eating them!

Paxillus involutus

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

QUICK ID TABLE: BROWN ROLL-RIM Paxillus involutus

CAP / FLESH

5-15cm across. Inrolled margin. Ochre – hazel-brown colour (often with darker rain post marks). Downy texture when younger, becoming smoother. Slimy when wet.

STEM

8cm x 0.8-1.2cm. Similar but lighter colour as cap. Stains darker with age.

GILLS / SPORE PRINT

Crowded and decurrent. Light ochre to sienna. Bruises darker.
Spore Print: Sienna brown (see how to take a spore print here).

HABITAT / SEASON

In broadleaved woodland and on heaths. Late summer – late autumn.

EDIBILITY

Poisonous. Can be deadly. Regular consumption build up toxins within the body. Avoid.

Horse & Field Mushroom Imposter! – The Yellow Stainer

It’s a Sunday afternoon and I pass by a grass verge near my house. My heart jumps at the sight of a huge cluster of (what seem to be) Horse mushrooms or possibly Field mushrooms, but this is no field, just a grassy verge near trees at the side of the road! I was without a basket or bag so like a kid in a sweet shop I scooped up a good share, leaving some to drop their spores.

But my dreams of a nice fry up or even a creamy mushroom soup are soon quaffed because I suddenly realise these mushrooms are not what they appear to be. I wait until I get home around the corner to double check. Read on…

Image of yellow marking on Agaricus xanthodermus

Chrome yellow staining on cap edge. Bulbous base.

I’m not surprised at all that the Yellow Stainer (Agaricus xanthodermus) is responsible for the most cases of mushroom poisoning in this country. Although this evil twin of our favourite field, wood and Horse mushrooms is not deadly it can keep you in the loo for longer than you normally do! Gastric symptoms can persist for up to 24 hours. Fortunately I have not been caught out yet, but some people after consumption usually get away with only mild upset or sometimes have no reaction at all. My Uncle once told me “Ooh, I don’t get along with those Yellow Stainers – don’t like ’em” . Let’s hope that it was only his palette they offended – I didn’t ask!

So how on earth can I identify this poisonous peril when compared to a Horse mushroom? I hear you all cry!

Don’t rely on the ‘overall look’. They differ in colour from pure white to brown/grey, scaly and smooth, tall and short and so on. Horse mushrooms can display some paler yellow on the cap and stem – so if you do see some yellow it’s not always a bad thing.

Both the Horse Mushroom and Yellow Stainer ‘bruise’ yellow (There’s hardly any yellow about the Field mushroom). But the Yellow Stainer has a stronger chromium yellow once bruised. If you rub the cap with your thumb, there will be a very noticeable colour change. But the crunch test for me is at the very base. Take a knife to the very bottom of the stem (the base is more bulbous than the others) and cut in half (see picture below). If the colour changes to a vivid yellow, then you’ve got yourself a Yellow Stainer. Horse and Field mushrooms do not stain at the base like this.

Other good ID tips are:
1. The smell is an unpleasant (phenol/inky smell more apparent when being cooked)
2. The ring on the stem is large and floppy.
3. Before the veil drops it does not have the ‘cogwheel’ pattern like the Horse Mushroom.
4. Gills when very young are white unlike the Horse and Field mushrooms which are pink

In addition to point 3 – if you’re new to collecting mushrooms, avoid very young specimens as they also can be confused with much more poisonous (even deadly) young toadstools.

The Yellow Stainer - Poisonous UK mushroom

Horse and Field Mushroom lookalike – The Yellow Stainer. Notice the chrome yellow colouring at the base of a cut stem.

Large ring of Yellow Stainer mushroom

On open caps: The ring on the Yellow Stainer is noticably large and floppy. The Field Mushroom’s ring is a fine torn frill. The Horse Mushroom’s ring is formed of a double membrane. The lower part is ‘star shaped’

Quick ID checlist for Agaricus Xanthodermus.

The Genus AGARICUS (Wood Mushrooms/Mushrooms): Characteristics to look out for:

• Many discolour yellowish, reddish or pinkish when cut or bruised.
• Those that discolour bright/chrome yellow should be avoided for consumption.
• Gills in young specimens are often pink (white in a few) – maturing darker brown.
• Make note of any smells, such as aniseed or a typical strong ‘supermarket’ mushroom smell.