Brown roll-rim

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iBrown roll-rim

Scientific classification

Kingdom:	Fungi
Phylum:	Basidiomyota
Class:	Basidiomycetes
Order:	Boletales
Family:	Paxillaceae
Genus:	Paxillus
Species:	P. involutus

Binomial name

Paxillus involutus
(Batsch ex Fr.) Fr.

Paxillus involutus mycological characteristics:	?
Image:Gills icon.png gills on hymenium
Image:Depressed cap icon.png cap is depressed
Image:Decurrent gills icon2.png hymenium is decurrent
Image:Bare stipe icon.png stipe is bare
Image:Brown spore print icon.png spore print is brown
Image:Mycorrhizal ecology icon.png ecology is mycorrhizal
Image:Poisonous toxicity icon.png edibility: poisonous

The Common- or Brown roll-rim, Paxillus involutus, also known as the Poison pax, is a mushroom previously thought to be edible with some unusual recently-discovered poisonous properties. It can cause a haemolysis which can be fatal. It often grows near edible mushrooms as well which makes it harder to identify by amateur mushroomers.

1 Identification
2 Habitat
3 Toxicity
4 References
5 External links

[edit] Identification

The cap, initially convex then more funnel-shaped with a depressed centre and rolled rim (hence the common name), is brown in colour and 4-10 cm wide. The narrow brownish yellow gills are decurrent and forked, darkening when bruised. It has a mild odour and taste. The spore print is brown. The stipe can be crooked and brownish or greyish yellow in colour.

[edit] Habitat

The brown roll-rim can found growing on lawns and old meadows, as well as deciduous and coniferous woodlands in Europe and North America in summer and autumn. It is an uncommon mushroom.

[edit] Toxicity

Previously deemed edible after cooking (it can cause gastic upset when raw), Flammer in 1980 discovered an antigen within the mushroom which stimulates an autoimmune reaction causing the body's immune cells to consider its own red blood cells as foreign and attack them. This results in dangerous haemolysis, which has been fatal.<ref>Winkelmann M, Borchard F, Stangel W & Grabensee B. (1982)Fatal immunohaemolytic anaemia after eating the mushroom Paxillus involutus (author's translation from German)Dtsch Med Wochenschr. 107(31-32):1190-4 online abstract</ref>

The use of corticosteroids may be useful in treatment.<ref>Olesen LL. (1991) Poisoning with the brown roll-rim mushroom, Paxillus involutus (Translated from Danish) Ugeskr Laeger. 153(6):445</ref>