Geoglossum atropurpureum – dark purple earthtongue
Geoglossum atropurpureum Pers.
Family: Geoglossaceae
Earth tongues are one of the groups of fungi that are indicators of old unfertilised grassland. They cannot be identified without microscopic examination, but this species is very distinctive under the microscope.
In brief
- There are 11 records of this species in Northern Ireland
- Found in old semi-natural grasslands in habitats ranging from upland acidic grassland to sand dunes to neutral grasslands (a churchyard)
- Fruiting bodies have been recorded from October and November in Northern Ireland
- This is a scarce fungus which is rare elsewhere in Ireland and is dependent on habitats which have declined and are 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
This species is called Thuemenidium atropurpureum in many identification books and Microglossum atropurpureum in others, but it is now included in Geoglossum. Another species listed in some keys, Microglossum robustum, is regarded as a synonym of G. atropurpureum.
G. atropurpureum is like a black finger sticking out of the ground and can be up to 6cm high. In sand dunes, it can be much smaller with a very irregular shape. It is usually black in Northern Ireland, but can be purplish-black as well. This latter colour would lead to a suspicion of G. atropurpureum that would have to be confirmed microscopically. As it is an ascomycete (spore shooter), it forms spores on the outside of the fruiting body. These have to be examined to be able to identify the species. Most species of Geoglossum have dark spores that are long and narrow with 3-12 perpendicular divisions (septa). This species has colourless short spores that are often only 1-2 septate, only with age becoming up to 6 septate. It is also marked by brownish matter mixed up with the spores and cells unlike many other Geoglossums which contain grey / black matter.
Life cycle
It has been recorded in Northern Ireland from 9 October to 7 November but most of the records are from early November. Earth tongues typically appear late in the season with a peak in November and are often found in December as well, so this species is likely to be found late in the season.
Similar species
It is almost impossible to tell black earth tongues apart without looking under the microscope. Geoglossum glutinosum and G. peckianum have a markedly viscid (slippery) stem and species of Trichoglossum have jet black needle-like structures (setae) projecting from the fruiting body which can be seen with a hand lens. They cannot, however, be identified to species level without microscopic identification.
How to see this species
This species has been found mainly in upland areas with the exception of Cloghy Dunes on the Ards Peninsula. With the exception of this site, it has a markedly northern distribution in Northern Ireland, being found only in the uplands of Antrim and Londonderry. The best sites to see it are Binevenagh NNR, Kebble NNR, Slemish Mountain and Agnew’s Hill. It is found in old semi-natural grasslands in habitats ranging from upland acidic grassland to sand dunes to neutral grasslands. Fruiting bodies have been recorded from October and 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 (11 records) and the British Isles although records are more concentrated in upland hill pastures in the north and west. It is found in only 12 countries across Europe with Scandinavia being its stronghold.
Why is this species a priority in Northern Ireland?
- It is a scarce species which is rare elsewhere in Ireland.
It is an excellent indicator of old unfertilised grasslands. This habitat is known to be decreasing in extent from the Northern Ireland Countryside Survey. It is also listed as one of the proposed species of fungi for inclusion onto the Berne Convention.
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
- Three of the eleven sites are designated as either ASSIsor NNRs
- 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 the species
- Publicise conservation value and management requirements of this species amongst managers of existing / potential sites
- Research into ecological requirements.
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 david.mitchel@nifg.org.uk.
Further information
Links
Northern Ireland Fungus Group
Berne Convention - fungal candidates
Northern Ireland Habitat Action Plans
Literature
Hansen, L. and Knudsen, H. (2000). Nordic Macromycetes Vol. 3 Nordsvamp, Copenhagen.
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