Northern Ireland's Priority Species

Microglossum olivaceum – olive earthtongue

Microglossum olivaceum

Microglossum olivaceum (Pers.) Gillet
Family: Geoglossaceae

Earth tongues are one of the groups of fungi that are indicators of old unfertilised grassland. Unlike most other members of this group, this species is usually easy to identify due to its unusual colours.

In brief

  • This species is known from 12 sites in Northern Ireland

  • Found in old semi-natural grasslands in habitats ranging from upland acidic grassland to sand dunes to neutral grasslands and man-made habitats like churchyards

  • Fruiting bodies have been recorded from September to November in Northern Ireland

  • This is a UK Priority Species and its presence indicates that the site is likely to be rich in other fungi of conservation concern

  • The main threats are due to agricultural intensification (especially the application of fertilisers), habitat neglect, reduction of habitat and lack of awareness.

Species description
The form of this species is typical of all the earth tongues – a narrow stem supporting a wider, often flattened cylindrical head looking like a tongue sticking out of the earth. It is, however, the colours of this species that makes it stand out from the rest of the group. Instead of black, the colours are very variable, ranging from red brown to green and often containing a mix of these colours in the one fruiting body. Sometimes it can lack the green colours (e.g. the Cloghy Dunes population) when it is sometimes called M. fuscorubens, but this is now regarded as a synonym and not a separate species. Likewise, some colour variants can be carmine pink and this variety has been called Geoglossum carneum in the past. Under the microscope, the spores are colourless and usually non-septate (perpendicular divisions within the spores).

Life cycle
The earliest fruiting body recorded in Northern Ireland was found on 27 September and the latest on 24 November. Earth tongues typically appear late in the season with a peak in November and are often found in December as well, so it would not be surprising if this species is also found so late in the season. Some populations occur every year in the same place at the same time of year, and so can be refound with ease if you know where to look.

Similar species
The only other species that this could be confused with is Microglossum viride which has a brighter green colour. M. viride has a stem that is often covered in green scales compared to the smooth stem of M. olivaceum, has longer spores and is usually found in woods and not grasslands. This latter distinguishing feature cannot be relied on however, as grassland species are also found in woods in Northern Ireland so the other features should always be checked.

How to see this species
This species has been found in a variety of habitats around Northern Ireland such as upland acidic grassland, sand dunes, neutral grasslands and churchyards. Sites like Cloghy Dunes on the Ards Peninsula, Barnett’s Park in Belfast, Binevenagh NNR, Crossmurrin NNR in Fermanagh and Kebble NNR on Rathlin Island are all good sites to see this species. A lot of the records from Great Britain are from calcareous grassland, so this habitat is a likely source of more records in Northern Ireland. Fruiting bodies have been recorded from September to November in Northern Ireland. Relevant access permissions should always be sought prior to visiting any sites.

Current status
This is a widespread but rare species across Northern Ireland (12 sites) and the British Isles.

Why is this species a priority in Northern Ireland?

  • UK Priority Species.

It is an excellent indicator of old unfertilised grasslands. Data from the Northern Ireland Countryside Survey would indicate that this habitat is decreasing in extent.

Threats/Causes of decline
The main reasons for decline are agricultural intensification (primarily the application of phosphorus and other nutrients) and habitat loss. Grassland neglect where the sward becomes rank also restricts fruiting, although it is not clear if this affects the organism under the ground.

Conservation of this species

Current action
There is a UK Species Action Plan which was published in 1999

  • Five of the twelve sites are covered by either ASSIor NNRdesignations

  • A grassland fungi survey funded by EHS for the whole of Northern Ireland 2002-04 produced a good overview of the distribution of the species

  • Production of Grassland Fungi conservation leaflet by Fungal Conservation Forum

  • Implementation of the Northern Ireland habitat action plans for Lowland Meadow, Lowland Dry Acid Grassland, Calcareous Grassland and Coastal Sand Dunes.

Proposed objectives/actions

  • Maintain the number of viable populations of this species

  • Publicise conservation value and management requirements of this species amongst managers of existing / potential sites

  • Research into ecological requirements.

What you can do
It is easily identifiable, hence it could be used to find other high quality sites for grassland fungi. Any new records should be reported to the Northern Ireland Fungus Group. Records can be sent in using online recording forms or by contacting

Further information

Northern Ireland Fungus Group

Waxcap information

NBN Gateway

British Mycological Society

British Waxcap website

UK Biodiversity Action Plan

Northern Ireland Habitat Action Plans

Kebble NNR

Binevenagh NNR

Hansen, L. and Knudsen, H. (2000). Nordic Macromycetes Vol. 3 Nordsvamp, Copenhagen.

Evans, S. (2004). Waxcap-grasslands – an assessment of English sites. English Nature Research Report No 555.

McHugh, R., Mitchel, D., Wright, M. and Anderson, R. (2001). The fungi of Irish grasslands and their value for nature conservation. Proceedings of the Royal Irish Academy, 101B (3), pp. 225-242. download as pdf from RIA website 650kb.

Newton, A.C., Davy, L.M., Holden, E., Silverside, A., Watling, R. and Ward, S.D. (2002). Status, distribution and definition of mycologically important grasslands in Scotland. Biological Conservation 111, 11-23

Text written by:
David Mitchel

iNaturalist: Species account : iNaturalist World Species Observations database