Leucobryum glaucum | Large White-moss



Conservation status

Future Prospects
Overal Assessment of Conservation Status
Overal trend in Conservation Status

Source: NPWS 2013.

IUCN Conservation Status
Ireland (1)
Least Concern
Europe (2)
Not evaluated
Global (2)
Not evaluated

Sources: (1) Lockhart, N., Hodgetts N., and Holyoak D., (2012); (2) The IUCN Red List of Threatened Species. Version 2014.2.

Legal status

Protected by the following legal instruments:

  • Habitats Directive [92/42/EEC], Annex V.

Native status


Species Biology


A fairly remarkable species. This can form very large hummocks to 50cms high and to 1m across but usually smaller. Leaves are between 6 and 9mm long and largely composed of the central nerve or 'costa'. Leaves are un-toothed. Hummocks have a glaucous green look when wet, greenish white when dry.

In Leucobryum glaucum the lower, broader part of the leaf is longer than the upper, almost tubular, part of the leaf. The related Leucobryum juniperoideum has the lower part of the leaf shorter than the upper part; it also forms less 'neat' hummocks. In Ireland neither species produces capsules with any regularity.

Sources: Atherton, I., Bosanquet, S., Lawley, M.,  (2010). Smith, A.J.E. (2004).


Leucobryum glaucum is strongly calcifuge. Other than that it has a broad ecological range. It occurs in wet and dry acid woodlands, as well as bogs, heaths and poor fen.

Habitats include but are not necessarily limited to;

  • Dry siliceous heath (HH1)
  • Wet heath (HH3)
  • Montane heath (HH4)
  • Raised bog (PB1)
  • Upland blanket bog (PB2)
  • Lowland blanket bog (PB3)
  • Cutover bog (PB4)
  • Eroding blanket bog (PB5)
  • Oak-birch-holly woodland (WN1)
  • Oak-ash-hazel woodland (WN2)
  • Yew woodland (WN3)
  • Wet pedunculate oak-ash woodland (WN4)
  • Riparian woodland (WN5)
  • Wet willow-alder-ash woodland (WN6)
  • Bog woodland (WN7)
  • Highly modified /  non-native woodland (WD)
Source: NPWS 2013; Fossitt, J.A. 2001.

Life stages


Classic alternation of generations with diploid sporophyte and haploid gametophyte generations. In mosses the haploid gametophyte is the longer lived and obvious plant seen in the field.The sporophyte is the short lives seta (stalk) and capsule.

In Leucobryum glaucum male and female sex organs are produced on separate plants, with fertilization producing the diploid sporophyte. Meiosis of spore mother cells produce haploid spores. Spores germinate into a filamentous 'protonema' which will eventually produce the familiar moss gametophyte. Leucobryum glaucum displays sexual dimorphism with the male plant tiny and growing on the female plant.

In Ireland the sporophyte generation of Leucobryum glaucum is rarely produced. Other non-sexual methods of reproduction apart from by fragments are not known.

Sources; Porley, R. Hodgetts N., 2005; Smith, A.J.E., 2004.

Threats faced

In the Article 17 Habitats Directive reporting for the period 2007-2012 no threats or pressures were identified for Leucobryum glaucum.

Source: NPWS 2013.

Conservation actions

In the Article 17 Habitats Directive reporting for the period 2007-2012 no Conservation Measures in place or being implemented were identified for Leucobryum glaucum.

Source: NPWS 2013.

In the 2012 Irish Bryophyte Red List no Conservation Actions were listed for Leucobryum glaucum.

Source: Lockhart, N.,Hodgetts N., and Holyoak D., (2012)


World distribution(GBIF)

Distribution is shared between parts of mainland Europe, Scandinavia the British Isles and eastern North America with relatively isolated records in South America and Asia.  

Accuracy of world distribution shown in the Global Biodiversity Information Facility (GBIF) map below will be constrained by, amongst other factors, data held but not shared by countries and organizations not participating in the GBIF.

Irish distribution

Widespread distribution throughout Ireland with a stronger concentration of records towards the west coast and in the centre of the country. 

Temporal change

Records submitted to Data Centre in 2020

The following map is interactive. If you would prefer to view it full screen then click here.

How can you help

The National BiodiversityData Centre is trying to improve our knowledge on the distribution of Leucobryum glaucum in Ireland. Should you observe the the species, please submit sightings to add to the database. Detailed observations will assist us gaining a better insight into where Leucobryum glaucum  is most abundant in Ireland and we might also be able to detect regional variations. Please submit any sightings and photographs at:

All records submitted online can be viewed on Google Maps – once checked and validated these will be added to the database and made available for conservation and research.

Further information

For further information contact Dr. Liam Lysaght



Atherton, I., Bosanquet, S., Lawley, M.,  (2010). Mosses and Liverworts of Britain and Ireland a field guide. British Bryological Society.

Fossitt, J.A. (2001) A Guide to Habitats in Ireland. The Heritage Council.

Lockhart, N., Hodgetts, N. & Holyoak, D. (2012) Ireland Red List No.8: Bryophytes. National Parks and Wildlife Service, Department of Arts, Heritage and the Gaeltacht, Dublin, Ireland.

NPWS (2013) The Status of EU Protected Habitats and Species in Ireland.  Species Assessments Volume 3. Version 1.0. Unpublished Report, National Parks & Wildlife Services. Department of Arts, Heritage and the Gaeltacht, Dublin, Ireland.

Porley, R. and Hodgetts N. (2005) Mosses & Liverworts, Collins.

Smith A.J.E. (2004) The Moss Flora of Britain, Second Edition. Cambridge University Press.

The IUCN Red List of Threatened Species. Version 2014.2. Downloaded on 17 September 2014.