Northern Ireland's Priority Species

Hygrocybe lacmus – the grey waxcap

Hygrocybe lacmus

Hygrocybe lacmus (Schumach.) P.D. Orton & Watling
Family: Tricholomataceae

This is a rare ‘Waxcap’ fungus, typical of old unfertilised grasslands, a habitat that is greatly under threat. Although it does not have the bright colours typical of this group, it is usually found in sites with a high diversity of waxcaps hence it is a good indicator species.

In brief

  • Only found in two sites in Northern Ireland

  • Found in old semi-natural grasslands of high conservation value

  • It has been recorded in Northern Ireland in November and December, although in Great Britain it has been recorded throughout the late summer / autumn months

  • It has to be carefully identified due to confusion with other species

  • It is one of the rarest species of this important group of fungi and is found only on sites of rich fungal diversity

  • 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 fruiting body can be 6cm wide and 7cm tall and often grows in small groups. The cap is grey, smooth and quite greasy with a striate cap margin (where the gills can be seen through the cap at the edge of the cap). It is hygrophanous which means that the cap discolours and changes appearance when it dries out. The gills are thick, pale grey and are decurrent curving down the stem. The stem is smooth and white although the base of the stem can sometimes be cream to buff. The taste can be rancid and the smell unpleasant and these are important identification features. To identify this species with certainty, it is necessary to look at it under the microscope and to check its spore size. It is thought to be a saprotroph, breaking down dead grass and moss thus playing an important role in the nutrient cycle. It is called H. lacma, H. subviolacea or Cuphophyllus lacmus in some identification books.

Life cycle
The earliest fruiting body recorded in Northern Ireland was found on 9 November and the latest on 12 December. However, this apparent late fruiting pattern is not seen elsewhere and it may well fruit from August to December like many other waxcaps.

Similar species
H.lacmus is very close to another more common species, H. flavipes. Indeed, prior to the late 1980’s, many people recorded both species as H. lacmus leading to much confusion when interpreting the true distribution of this species. H. flavipes can often be distinguished by a noticeable yellow base to its stem, but H. lacmus can have a buff base to the stem leading to confusion. However, the stem of H. flavipes is also fibrillose, not smooth, the taste and smell are neutral and the spores are rounder (hence specimens should be microscopically examined).

How to see this species
This species has only been found in Northern Ireland at Windy Hill in the Belfast Hills and Windy Gap near Downhill in County Londonderry. The grass sward is usually short, moss rich and poor in nutrients. It has been recorded in Northern Ireland in November and December, although in Great Britain it has been recorded throughout the late summer/autumn months. Relevant access permissions should always be sought prior to visiting any sites.

Current status
This species is only found in two sites in Northern Ireland. It is a rare species across the British Isles although due to taxonomic changes, its true distribution is hard to determine.

Why is this species a priority in Northern Ireland?

  • Rare and declining with Northern Ireland being the Irish stronghold.

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

  • 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 and Calcareous Grassland.

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
This is an important indicator species but one that is difficult to identify. 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

Waxcap information

NBN Gateway

British Mycological Society

British Waxcap website

Northern Ireland Habitat Action Plans

Boertmann, D. (1995). The Genus Hygrocybe. Copenhagen, The Danish Mycological society. This is the best identification guide for the group.

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

Griffith, G.W., Easton, G.L. and Jones, A.W. (2002). Ecology and Diversity of Waxcap (Hygrocybe spp.) Fungi. Botanical Journal of Scotland, 54(1), pp. 7-22. download as scanned pdf file 3.8Mb.

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