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
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?
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
Proposed objectives/actions
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 david.mitchel@nifg.org.uk.
Further information
Links
Northern Ireland Fungus Group
Northern Ireland Habitat Action Plans
Literature
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