Northern Ireland's Priority Species

Armillaria ectypa – marsh honey fungus


Armillaria ectypa (Fr.) Lamoure
Family: Marasmiaceae

This species is found in wet, often base rich habitats and appears to be extremely rare across Europe. It is not a very distinctive species, but its habitat requirements help in its identification.

In brief

  • This is a UK Priority Species

  • Only found on one modern site on the Garron Plateau, County Antrim, this being one of the four confirmed sites in the British Isles

  • Found in a base rich flush on the blanket bog

  • Found on the Garron Plateau between early and mid September

  • The main threats at the Garron Plateau are a lack of understanding of its ecological requirements, the wrong grazing regime, and any land use change that could lead to the site drying out.

Species description
The cap of the fruiting body can be up to 10cm wide and the stem 10cm tall at its maximum. The cap is convex to fairly flat, sometimes with a depressed centre with age and it has a yellowish-brown to brown colour. The centre of the cap can be scaly and the edge of the cap can be striate with the gills visible through the cap. It is hygrophanous, coming much paler in colour when drying and quite thin with little flesh. The gills are cream to pinkish and can curve downwards where they join the stem, although often they join the stem at 90°. The stem is pale brownish and unlike the common honey fungus, has neither a ring nor rhizomorphs or ‘bootlaces’ attached to the base of the stem. It can grow in dense clumps or singly. It has a white spore print.

Life cycle
It has been found in early to mid September on the Garron Plateau although in Great Britain, it has been recorded between July and October.

Similar species
Other species of Armillaria are noted by usually having a ring, distinct rhizomorphs or “bootlaces” extending from the base of the stem and a different habitat (usually in woods, gardens or on dead wood). In a fen or on a bog, fruiting body size, form (e.g. flat to convex cap often growing in clumps) and the white spore print rule out most other species with the exception of Tephrocybe (Lyophyllum) palustris which is smaller with a narrower stem and various species of Clitocybe which have to be carefully checked for microscopically.

How to see this species
This has been found on the Garron Plateau east of Dungonnell Dam on the base rich flushes, between early to mid-September. This species could well be found elsewhere in the uplands of Northern Ireland or in base rich fens which have not necessarily been looked at by mycologists. Relevant access permissions should always be sought prior to visiting any sites.

Current status
There are two old records of Clitocybe ectypa, a synonym of Armillaria ectypa, from Donard Park and Tollymore Forest Park from the 1880s. These records are, however, dubious as the habitat does not seem to match the requirements of this species unless the actual records were from the mountain flanks above these parks. The Garron Plateau record is its only confirmed Irish record and only one of four such records in the British Isles.

Why is this species a priority in Northern Ireland?

  • Listed as a UK Priority Species

  • Rare with 25% of UK population.

Threats/Causes of decline
The main threats are a lack of understanding of its ecological requirements, anything that may lead to the site drying out and possible changes in grazing pressure. Such flushes are often favoured places for sheep to graze and on one visit most of the fruiting bodies of A. ectypa were broken and damaged possibly due to sheep.

Conservation of this species

Current action
There is a UK Species Action Plan for this species which was published in 1995.

  • The single site is an ASSIand SAC

  • Implementation of the Northern Ireland Habitat Action Plans for blanket bog and fens.

Proposed objectives/actions

  • Research into ecological requirements — this is the single most important issue as this would allow informed decisions to be made about grazing pressures and other management issues

  • Maintain and monitor existing population

  • Targeted survey at the correct time of year in similar habitats.

What you can do
Some species of fungi can be difficult to identify, but if you are interested, please contact the Northern Ireland Fungus Group for details of how to record fungi. Records can be sent in using online recording forms or by contacting

Further information

Northern Ireland Fungus Group

British Mycological Society Fungal Records (UK wide data)

UK Biodiversity Action Plan

Garron Plateau ASSI

Northern Ireland Habitat Action Plans

Bas, C. et al. (1995). Flora Agaricina Neerlandica Vol. 3. Leiden. The Netherlands.

Ainsworth, M. (2003). Report on the marsh honey fungus, Armillaria ectypa, a UK BAP species. English Nature Research Reports No. 540 English Nature Publications.

Ainsworth, M. (2004). BAP Fungi Handbook. English Nature Research Reports No. 600 English Nature Publications.

Evans, S.E. (2002). Conservation Corner. Field Mycology 3: 143-145.

Text written by:
David Mitchel

iNaturalist: Species account : iNaturalist World Species Observations database