Timebomb Toadstool – The Brown Roll-Rim

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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.

Tree slippers – The Giant Polypore

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Walking along a woodland path, the adjacent foliage was heavily overgrown. But something still caught the corner of my eye at the base of a large oak tree. At first, I thought people had left some rubbish, considering the size, but as I removed the overgrowth (receiving many lovely nettle stings!) the picture became clearer.

Meripilus giganteusThis was indeed a Giant Polypore (Meripilus giganteus or Polyporus giganteus) occupying a good half of the tree’s circumference. Older parts on one side and younger ‘new’ born’ specimens emerging on the other.

A common mistake would be to confuse this bracket fungus with Hen of the Woods (Grifola frondosa) but on comparing notes, you’ll realise that these things are just too damn big! And the ones featured here will grow bigger still.

The fruiting bodies of this Polypore branch out in clumps. Each clump shares the same short and chunky stem, at the end of which are numerous fan-shaped caps ranging in size from 40 – 90cm in diametre, but are relatively thin compared to this width. They’re quite tough (but flexible) to prize away from the central stem, so a good sharp knife is in order!

Apart from their large size, the caps have reliable and distinctive markings. Their light brown ‘overall’ colour (which darkens with age) display several concentric, light/dark zones. On closer inspection you’ll see a layer of very fine brown scales. The edges are fanned or rosette-like and slightly grooved.

The Giant Polypore might not be as tasty as Chicken of the Woods but it is edible. It does smell quite nice but can taste quite bitter. But just like the Beefsteak Fungus, there maybe be a cooking preparation method to make this taste alot better. I haven’t tried myself, but it’s worth a go I think.

Keep a look out for these beauties this autumn. They can be found at the base of (mainly) beech or oak trees (or nearby, emerging from the underground roots) and sometimes on stumps. If you do take some samples you’ll notice after time the pores on the underside turn blackish where touched or bruised. Although unsightly, I don’t believe this affects the final taste, if prepared like the Fistulina hepatica for example.

Polyporus giganteus. Giant Polypore

The Giant Polypore – Older specimens appear darker brown (top) while younger ones are a lighter shade (bottom). Note the pure white pores underneath (middle) showing a much younger specimen on the right.

QUICK ID TABLE: GIANT POLYPORE Meripilus giganteus / Polyporus giganteus

FRUITING BODY

50-80cm across. Made up of rosette formations with short stems fusing at a common base. Each of the fan shaped caps range from 10-30cm across / 1-2cm thick. Upper surface concentrically zoned light and darker brown. Covered in fine brown scales; radially grooved. Flesh is white, soft and fibrous.

STEM

See above.

PORES / SPORE PRINT

Late in forming; 3-4mm, sub circular shape. White(ish) bruising blackish.
Spore Print: White (see how to take a spore print here).

HABITAT / SEASON

At the base of deciduous trees or stumps; mainly beech or oak. Can grow from roots of tree away from trunk appearing indepent of tree.

EDIBILITY

Edible. Can be bitter.

The Genus POLYPORUS & Related (Polypores etc): Characteristics to look out for:

• Nearly all are bracket fungi, but a few are with typical cap and stem but with pores instead of gills underside.
• Usually tough or hard and woody. Some are softer and edible.
• Many are perennial or annual.