Microglossum olivaceum

Microglossum olivaceum Copyright Mark Wright

This is a grassland species that is one of the group known to be good indicators of ancient unfertilised grassland. It is also a Biodiversity Action Plan Species, a species that is thought to be under threat due to its declining population. It is an ascomycete or "spore shooter" and is obviously related to the more common black earth tongues (Geoglossum spp or Trichoglossum spp.) There is only one other species of Microglossum: M.viride, but this is usually found in woodlands. The two are told apart by the nature of their stipe (stalk) - smooth in olivaceum and squamulose or scurfy in viride - the size of their asci (the structures that house the spores) - shorter than 95Ám in olivaceum and longer than 110Ám in viride - the spore size 13-17 x 3.5-5Ám in olivaceum and 16-22 x 5-6Ám in viride (Source: Spooner & Nauta's key to Geoglossaceae).  There are possibilities that there may be other species in this group eg fuscorubens, but these are possibly just colour varieties of M.olivaceum. This variety of form is very evident. Some are pure brown (see below from Cloghy dunes in Co.Down) whilst others are partly brown and turquoise green (see above from Kebble NNR on Rathlin Island) or below. 

This species had only one recent record in Northern Ireland until last year (2000) when it suddenly appeared on a number of sites. It was previously only known from Cloughy dunes and then was found on Crossmurrin NNR in Co.Fermanagh, Binevenagh NNR in Co.L'derry and Kebble NNR on Rathlin Island. There is another record from Inishfendra in Crom Estate, Co.Fermanagh but this is doubtful as the specimen was so young that it was not possible to confirm the record.

In summary, it has been recorded from the following sites:

Montalto Estate, Ballynahinch, Co.Down, 27 September 1930. Not refound here since.

Cloghy Dunes, Co.Down, recorded every year 1998-2000 in November and in August 2002.

Crossmurrin NNR (calcareous grassland), Co.Fermanagh, October 2001

Kebble NNR (acid upland grassland), Rathlin Island, Co.Antrim, October 2001

Binevenagh NNR, (acid upland grassland), Co.L'derry. November 2001

Barnett's Park, Belfast. October 2001

Ballycastle Coalfields (near Fair Head, Co.Antrim), September 2002


Any records of this species should be passed to me please at david.mitchel@nifg.org.uk


To see its Biodiversity Action Plan, go to the UK Biodiversity website

Microglossum olivaceum Copyright Mark Wright

Microglossum olivaceum Copyright David Mitchel

Current Distribution of Microglossum olivaceum

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