Lactarius scrobiculatus (Scop.) Fr. - Spotted Milkcap

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

Lactarius scrobiculatus, southern France

This beautiful, woolly-fringed mushroom is yet another of the many large milkcap species that are mycorrhizal with spruce trees. Unlike the very similar Yellow Bearded Milkcap Lactarius repraesentaneus, whose white latex (the milk-like liquid that oozes from cut or broken gills) turns lilac or purple as it dries, the latex from Lactarius scrobiculatus changes from white to sulphur yellow on exposure to air. There are other subtle differences, too - for example the spores are smaller than those of Lactarius repraesentaneus.

Lactarius scrobiculatus, France

Distribution

This milkcap was last formally recorded in Britain and mostly seen in Scotland. Lactarius scrobiculatus occurs also on mainland Europe, and a very similar (but perhaps not co-specific) milkcap in North America is referred to as Lactarius scrobiculatus var. canadensis.

The pictures shown on this page was taken under a spruce tree in mixed woodland near Besancon, in central France.

Taxonomic history

This milkcap was first validly described in 1772 by Italian mycologist Giovanni Antonio Scopoli, who gave it the binomial scientific name Agaricus scrobiculatus. (In the early days of fungal taxonomy most gilled fungi were initially placed in a giant Agaricus genus, now largely redistributed across many other genera.)

It was the great Swedish mycologist Elias Magnus Fries who, in 1838, transferred this species to the genus Lactarius, thereby establishing its currently-accepted scientific name of Lactarius scrobiculatus.

Synonyms of Lactarius scrobiculatus include Agaricus scrobiculatus Scop., and Agaricus intermedius Fr.

Toxicity

Although it is unlikely to cause death or long-term illness, this is a poisonous mushroom and should definitely not be gathered for eating because it can cause unpleasant stomach pains, sickness and a burning sensation in the throat. It almost goes without saying that in some parts of Europe these fungi are eaten after frequent boiling and discarding the water in order to reduce the level of toxins.

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 scrobiculatus comes from Latin scrobis, meaning a trench. The diminutive form scrobiculus is a small trench or pit (a planting hole, for example), and scrobicules is the technical name for those oval pits on the stem surface of a subgroup of Lactarius known as the 'Scrobiculati'.

Identification guide

Cap of Lactarius scrobiculatus

Cap

Initially convex, becoming centrally depressed or broadly funnel shaped but retaining a slightly inrolled margin, which is overhung by woolly strands; 5 to 15cm in diameter.

Cap surface is yellow or yellow-orange, with indistinct concentric rings of small scales appearing as dark-and-light colour zones; slimy, especially in wet weather. Bruised areas turn a dirty brown colour. The cap flesh is white and turns yellow on exposure to air.

Gills of Lactarius scrobiculatus

Gills

The adnate or shortly decurrent, crowded whitish gills eventually turn yellow or pale orange; when damaged they become stained by a copious creamy white latex that quickly turns sulphur yellow.

Stem of Lactarius scrobiculatus

Stem

3 to 6 cm long and 1.3 to 3.5cm in diameter; cylindrical or slightly clavate; slimy when fresh. The stem surface pale yellow with an extensive random covering of slightly darker oval hollows (known as scrobicules). The stem base is downy.

As with other members of the family Russulaceae, there is no stem ring.

 

Spores

Broadly ellipsoidal, 9-11 x 7.5-9µm; ornamented with low (<0.8µm) warts joined by ridges that do not form a complete reticulum.

Spore print

Cream.

Odour/taste

Faintly fruity odour; taste very hot and acrid.

Habitat & Ecological role

Mycorrhizal, often in small groups, with spruce trees.

Season

August to November in central Europe.

Similar species

Lactarius repraesentaneus produces latex that turn lilac; its spores are larger.

Lactarius torminosus has a pale pink to pinkish-orange woolly cap and grows under birches usually in damp soil.

Lactarius pubescens has a buff-white or cream woolly cap and grows mainly in damp grass under birch trees.

Reference Sources

Fascinated by Fungi, Pat O'Reilly, 2011

Funga Nordica, Henning Knudsen and Jan Vesterholt, 2008.

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

BMS List of English Names for Fungi.

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

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.

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