Mitrula paludosa Fr. - Bog Beacon

Phylum: Ascomycota - Class: Leotiomycetes - Order: Helotiales - Family: Helotiaceae

Mitrula paludosa, Bog Beacon

In Britain and Ireland this ascomycetous matchstick-like fungus is known as the Bog Beacon, while in the USA it is commonly referred to as the Swamp Beacon. Either way, there are no prizes for guessing that this little fungus occurs only in very wet places.

The role of these little club-like fungi in the natural world is that of recycler; they feed of rotting leaves and stems, helping to break them down into simple compounds that other plants can feed on.

Mitrula paludosa, Bog Beacon - yellow and orange forms


Infrequent but widespread in Britain and Ireland, Bog Beacon also occurs throughout most of mainland Europe as well as parts of Asia.

What I can confirm from personal experience is that you will not find Bog Beacon where the habitat is unsuitable, but neither should you assume that where the habitat is suitably boggy with plenty of rotting vegetation this ascomycete will appear: more often than not it doesn't.

Taxonomic history

The great Swedish mycologist Elias Magnus Fries described this ascomycetous fungus in his Systema Mycologica of 1821, in which he named it Mitrula paludosa. To the present day that remains the generally accepted scientific name for Bog Beacon. (It was Fries himself who established the genus Mitrula, and he made Mitrula paludosa the type species of this genus.)

During the past two and a half centuries various mycologists have placed this species in other genera. Synonyms of Mitrula paludosa include Leotia uliginosa Grev., Clavaria phalloides Bull., Clavaria epiphylla Dicks., Leotia epiphylla (Dicks.) Hook., and Mitrula phalloides (Bull.) Chevall.


The prefix Mitr- is a reference to a mitre, cap or headdress (and so,by implication, an indication of the shape of the fertile head or cap of this fungus), while the specific epithet paludosa means of swamp, marsh or bog.

Identification guide

Mitrula paludosa, closeup of caps and stems


The smooth yellow (sometimes orange-yellow) fertile head is of variable shape and can be subglobose, ovoid or club-shaped and up to 1cm tall.


Smooth, white, untapered and typically 2 to 3mm in diameter, the stems are up to 4cm tall.

Asci of <em>Mitrula paludosa</em>


100-150 x 8-9µm.

Eight spores per ascus; the spores are arranged in two irregular rows within the ascus.

Show larger image

Spore of Mitrula paludosa, Bog Beacon


Oblong-ellipsoidal, smooth, sometimes septate; 10-15 x 2-3µm; hyaline.

Spore print



Not distinctive.

Habitat & Ecological role

Saprobic on rotting leaves, twigs, mosses and algae in bogs, swamps, damp ditches and in the shallow margins of some weed-fringed lakes.


Early spring through to the end of summer.

Similar species

There are several very similar Mitrula species, separable only by microscopic examination.

Mitrula paludosa, Bog Beacon, Hampshire, England

Reference Sources

Fascinated by Fungi, 2nd Edition, Pat O'Reilly 2016, reprinted by Coch-y-bonddu Books in 2022.

Dennis, R.W.G. (1981). British Ascomycetes; Lubrecht & Cramer; ISBN: 3768205525.

Breitenbach, J. & Kränzlin, F. (1984). Fungi of Switzerland. Volume 1: Ascomycetes. Verlag Mykologia: Luzern, Switzerland.

Medardi, G. (2006). Ascomiceti d'Italia. Centro Studi Micologici: Trento.

British Mycological Society. 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.


This page includes pictures kindly contributed by David Kelly.

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