Hypholoma fasciculare var. fasciculare (Huds.) P. Kumm. - Sulphur Tuft

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Strophariaceae

Hypholoma fasciculare - Sulphur Tuft, central France

From April through to the first heavy frosts, a walk in mixed woodland rarely fails to reveal Sulphur Tufts fruiting on fallen trees, decaying stumps or, occasionally, hollow trunks of living trees.

This wood-rotting fungus is not a fussy feeder it tackles deciduous hardwoods as well as conifers apparently with equal relish, although it is most effective in rotting broadleaf trees (hardwoods), which generally have a higher cellulose content and rather lower lignin content than conifers.

Sulphur Tuft fungi on a conifer root

Sulphur Tuft fungi (in the USA the spelling in common use is Sulfur Tuft) are gregarious and tend to appear in large groups so tightly packed that the caps are unable to expand regularly. The tuft shown on the left is one such example; these jostling fruitbodies were growing beside the stump of a dead conifer, their mycellium having invaded the root system.

Displays of Sulphur Tufts can recur on large stumps for two or three years in succession before the timber is reduced to its hard core of lignin, at which point other lignin-eating fungi move in to finish it off.

Distribution

Very common in Britain and Ireland, Hypholoma fasciculare occurs also across most of mainland Europe, where it is most prevalent in northern and central countries. This wood-rotting species is common also in North America.

Sulphur Tuft fungi on conifer stump, Wales

Taxonomic history

Described scientifically in 1778 by British botanist and mycologist William Hudson (1730 - 1793), this common wood-rotting mushroom was initially given the name Agaricus fascicularis. (Most gilled fungi were initially placed in a giant Agaricus genus, now redistributed to many other genera.) Its current base name, Hypholoma fasciculare, dates from 1871, when Paul Kummer transferred it to the genus Hypholoma.

Synonyms of Hypholoma fasciculare var. fasciculare include Agaricus fascicularis Huds., Pratella fascicularis (Huds.) Gray, Hypholoma fasciculare (Huds.) P. Kumm., Agaricus sadleri Berk. & Broome, Naematoloma fasciculare (Huds.) P. Karst., and Hypholoma fasciculare f. sterilis J. E. Lange.

Above: Sulphur Tuft fungi swarming over coniferl tree stumps in central France.

A group of Sulphur Tuft fungi grong from buried timber

In 1923, J. E. Lange separated from the nominate form a variety of Sulphur Tuft which is named Hypholoma fasciculare var. pusillum J. E. Lange; it is a rare find in Britain. Synonyms of this variety of Sulphur Tuft include Naematoloma capnoides var. pusillum (J. E. Lange) Courtec., and Psilocybe fascicularis var. pusilla (J. E. Lange) Noordel.

Etymology

Hypholoma, the genus name, means 'mushrooms with threads'. It may be a reference to thev thread-like partial veil that connects the cap rim to the stem of young fruitbodies, although some authorities suggest that it is a reference to the thread-like rhizomorphs (root-like bundles of mycelial hyphae) that radiate from the stem base.

It hardly needs mentioning that the common name Sulphur Tuft is a reference to the bright sulphur-yellow colour of the caps of these fungi combined with their habit of growing in tightly bunched tufts.

Sulphur Tufts on a well-rotted tree stump

The specific epithet fasciculare comes from the Latin word fasces, a bundle of rods bound around an axe-head used by magistrates in ancient Roman magistrate as a symbol of authority and power. Fascism comes from the same source, implying a small group (or bundle) with imposed and centralised authority and power.

Toxicity

Very variable in cap size, the Sulphur Tuft fungus, Hypholoma fasciculare, is inedible with a very bitter taste. In Britain and Europe Hypholoma fasciculare has been linked to severe cases of poisoning and most probably at least one death; however, there seems to be little published information about the 'Fasciculol' toxins involved. Strangely, the same species in the USA is reported to be edible, although its extremely bitter taste ought to be quite effective as a deterrent for people with any taste buds at all.

Symptoms of poisoning by Sulphur Tufts

Although only very rarely fatal, poisoning by Hypholoma fasciculare is occasionally reported and it can result in severe symptoms, including not only stomach pains and nausea but also temprary paralysis and distorted vision. Sulphur Tuft fungi have such a bitter taste, however, that only the most determinied fungiphage is likely to want to eat them. Concealed within a meal of otherwise edible fungi it is possible that the bitter taste of Sulohur Tusts could go unnoticed. There is a delay of typically five to ten hours between ingestion of these fungi and the appearance of symptoms of poisoning.

Identification guide

Cap of Hypholoma fasciculare

Cap

Sulphur yellow, often tan towards the centre of the cap; convex or slightly umbonate, with dark velar remnants attached to the cap margin.  2 to 7cm in diameter.

The cap flesh is sulphur yellow and quite firm.

Gills of Hypholoma fasciculare

Gills

The crowded adnate gills of the Sulphur Tuft are initially sulphur yellow, becoming olive-green and progressively blackening as the spores ripen.

Stems of Hypholoma fasciculare

Stem

Stems of Hypholoma fasciculare are more or less concolorous with the cap, but rather browner towards the base; 5 to 10 mm in diameter, usually curved with length 5 to 12cm.

Spores of Hypholoma fasciculare, Sulphur Tuft

Spores

Ellipsoidal, smooth, 6-7 x 4-4.5μm; with a small germ pore.

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Spore print

Purplish-brown.

Odour/taste

Hypholoma fasciculare has a mushroomy but undistinctive odour and a very bitter taste. (If you taste this mushroom do not swallow any; please remember that it is inedible and capable of causing very unpleasant stomach upsets.)

Habitat & Ecological role

Sulphur Tuft is saprobic, feeding on stumps, felled trunks and other dead wood from broad-leaf trees and less commonly conifers. If you see tufts apparently growing in grass it is a certainty that buried roots or other timber and lying just beneath the soil surface. As the root systems of many broadleaf trees extend well beyond the leaf canopy, so also the Sulphur Tuft fungus can fruit quite a long way from the trunk of the decaying tree on which its mycellium is feeding.

Season

All through the year in Britain, but most abundant from June to November.

Similar species

Hypholoma lateritium, the Brick Tuft, is typically redder with yellow gills (rather than olive-green) that eventually become olivaceous-brown.

Hypholoma capnoides, Conifer Tuft, has pale grey gills with no hint of green.

Sulphur Tufts on the remains of old conifer roots

Above: Only a small mossy mound in the forest floor remains to show that a tree was once here, but Sulphur Tuft mushrooms still continue to find something to feed upon. Tree stumps can bear fruitbodies of Hypholoma fasciculare for several years in succession.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Funga Nordica: 2nd edition 2012. Edited by Knudsen, H. & Vesterholt, J. ISBN 9788798396130

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.

Other web pages about this species

Roger Phillips (UK)

Michael Kuo (USA)

Marek Snowarski (Poland)

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