Lactarius uvidus (Fr.) Fr.

Lactarius uvidus, Wales UK

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Russulales - Family: Russulaceae

Lactarius uvidus (which does not have a generally accepted common name) grows in wet places, mainly under willow and birch on acid soils. If asked to suggest a common name for this mushroom, it would have to be the Lilac-staining Milkcap.

Distribution

An infrequent find in southern Britain, Lactarius uvidus is rather more common in some parts of Scotland and in northern mainland Europe.

Lactarius uvidus, mature specimen, Wales

Lactarius uvidus is recorded also from the eastern side of North America, but whether the milkcaps (generally written as Milk Caps in the USA) are co-specific with their European counterparts is as yet unconfirmed.

Taxonomic history

This milkcap mushroom was first described in 1818 by the renowned Swedish mycologist Elias Magnus Fries who gave it the binomial scientific name Agaricus uvidus. Two decades later, in 1838, Fries transferred the species to its present genus, whereupon it became Lactarius uvidus, which is its currently-accepted scientific name.

Synonyms of Lactarius uvidus include Agaricus lividorubescens Batsch, Agaricus livens J.F.Gmel., Agaricus uvidus Fr., Galorrheus uvidus (Fr.) P.Kumm., and Lactarius lividorubescens (Batsch) Burl.

Etymology

The generic name Lactarius means producing milk (lactating) - a reference to the milky latex that is exuded from the gills of milkcap fungi when they are cut or torn. The specific epithet uvidus means damp or humid and is a reference to the habitat preference of this species.

Identification Guide

A young specimen of Lactarius uvidus displaying lilaceous latex stains on its gills

The lilaceous staining on damaged gills is a distinctive feature of this milkcap; it is very clearly visible on the gills of this pale young specimen (left).

Cap of Lactarius uvidus

Cap

Pale violet grey when young, this deceptive milkcap becomes much darker and browner as the fruiting body matures.

4 to 9cm in diameter, convex and then flat or slightly depressed, the caps are buff or lilaceous, darkening with age.

When cut, the firm flesh below the cuticle is buff but eventually turns lilaceous.

Gills of Lactarius uvidus

Gills

Shortly decurrent and fairly crowded, the pale gills darken with age. When damaged, the gills release a white milk that very slowly turns lilaceous as it dries.

Stem

6 to 25mm in diameter and 3 to 6cm tall, the pale stems are cylindrical and become hollow with age.

 

Spores

Subglobose to broadly ellipsoidal, 9-10 x 7.5-8.5 μm, hyaline; ornamented with broad ridges 0.5-1 µm tall; forming an incomplete reticulum.

Spore print

Pale cream.

Odour/taste

Slightly fruity but indistinctive odour; bitter taste.

Habitat & Ecological role

Under willow and birch in damp woodland; less frequently under conifers.

Season

August to October in Britain and Ireland.

Similar species

Lactarius quietus also has a buff cap, but it is found only under oaks and its milk does not turn lilac as it dries.

Culinary Notes

This distinctive species is bitter tasting, It is considered inedible and some say that it might be poisonous.

Reference Sources

Pat O'Reilly (2016). Fascinated by Fungi, First Nature Publishing

Jacob Heilmann-Clausen, Annemieke Verbeken, & Jan Vesterholt (1998). The Genus Lactarius (Fungi of Northern Europe—Vol. 2) The Danish Mycological Society.

Funga Nordica, Henning Knudsen and Jan Vesterholt, 2008.

Fungi of Switzerland, volume 6: Russulaceae, Kränzlin, F.

BMS List of English Names for Fungi.

Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers. (2008). Dictionary of the Fungi; CABI.

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

Other web authorities on this species

Roger Phillips (UK)

Michael Kuo (USA)

Russulales News (Italy)

Marek Snowarski (Poland)

Top of page...


Pat O'Reilly

If you have found this information helpful, we are sure you would also find our book Fascinated by Fungi by Pat O'Reilly very useful. Author-signed hardback copies at a special discount price are available here...

Other nature books from First Nature...