Sphagnum warnstorfii | Warnstorf's Bog-moss



Conservation status

Future ProspectsN/A
Overall  Assessment of Conservation StatusInadequate
Overall Trend in Conservation StatusStable
*All E.U. Sphagnum species  are identified as requiring assessment under the Habitats Directive. Guidelines on reporting for the Habitats Directive indicate that these species are required to be reported on as a group, unless a member state is of the opinion that individual species within the group may require special attention. In the Article 17 Habitats Directive reporting for the period 2007-2012 none of the named Sphagnum species of the Habitats Directive occurring in Ireland were identified as requiring special attention.

The Conservation Status in the table above is then for the Sphagnum genus in Ireland rather than for the individual species.

Sources: NPWS 2013; European Topic Centre on Biological Diversity.

IUCN Conservation Status
Ireland (1)Vulnerable [B2a, bii, iv]
Europe (2)**Not evaluated
Global (2)Not evaluated

**Although not published separately, an evaluation of 'Least Concern' at a European level is indicated in the Ireland Red List No.8: Bryophytes. This evaluation was carried out under the auspices of the European Committee for Conservation of Bryophytes.

Sources: (1) Lockhart, N., Hodgetts, N. & Holyoak, D. 2012; (2) The IUCN Red List of Threatened Species. Version 2014.3.

Legal status

Protected by the following legal instruments:

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

Native status


Species Biology


Members of the Sphagnum genus are distinguished from other moss species by the combination of the following, amongst other, characteristics;

  • The absence of rhizoids in the gametophyte, and the presence of groups of spreading and / or pendent branches (these groups referred to as fascicles) arranged at intervals along the main stem.
  • As well as chlorophyllose cells (chlorocysts) Sphagnum leaves have adapted large dead cells, 'hyaline' cells, that allow Sphagnum species plants to retain water in relatively large amounts.
  • The sporangium lacks the peristome seen in many other moss genera.
  • Rather than the seta (stalk) seen in other mosses, in Sphagnum species the spore bearing capsule is borne on a pseudopodium.
  • The top end of the plant, where new fascicles are formed, contains many young compact fascicles which give Sphagnum species a distintive 'mop-head' look. This terminal head is termed a capitulum.
  • The lack of a leaf mid-rib or 'costa'.

Sphagnum warnstorfii is one of a group of twelve Irish Sphagnum taxa (including 4 subspecies) that are often referred to collectively as section Acutifolia. In this group the defining characteristics are primarily microscopic e.g. that branch leaves have up to 3 large pores (between 8µm and 30µm) on the underside, and that chlorocyst shape is approximately triangular, the base of the triangle most visible from the upperside of branch leaves.

There are other characteristics that may aid identification in the field.

  • Branch leaves are not conspicuously hooded at the apex.
  • Stem cortex makes up less than 1/4 of the stem diameter.
  • Stem leaves, depending on species and / or conditions will have patches of narrow cells in the angles at the base of the leaves across between 20% and 80% of the width of the leaf base (apart from Sphagnum molle where these patches are absent).
  • All species in this section (apart from Sphagnum molle) have stem leaves appressed with the leaf apex directed towards the capitulum in normal growing conditions.
Within this section Sphagnum warnstorfii is most often a very striking deep crimson, although rarely it may  be largely green, although even then is likely to have some red colour also.

  • Stem leaves may be quite triangular towards the apex or 'pointed' lingulate in shape.
  • Stem may be red or green.
  • Branch leaves are rather ovate, sometimes narrowly so.
  • Branch leaves are usually very strongly 5 ranked.
  • Viewed from above, the capitulum is more often than not distinctly star shaped. Single developing branches may be seen between the rays of the ''star'
  • Capitulum is rather flat topped.
  • S. warnstorfii has 2 spreading branches and 1 to 2 pendent branches per fascicle.
  • Spreading branch leaves just below the capitulum are usually very straight.
  • Plant width, including fascicles, between 1 and 1.5cm.
  • Well grown shoots to 15cm long.
  • Capsules not recorded in Ireland or Britain.
  • Can be confused with S. capillifolium, particularly ssp. rubellum however that very often has branches below the capitulum curving slightly. S. capillifolium is also less likely to be found in the base rich environments S. warnstorfii requires.
  • The presence of S. teres and S. contortum in base rich conditions may indicate that a deep crimson sphagnum is S. warnstorfii.
  • Records for S. warnstorfii are really quite scarce in Ireland.

Sources: Atherton, I., Bosanquet, S., Lawley, M.,  2010; Lockhart, N., Hodgetts, N. & Holyoak, D. 2012a; Smith, A.J.E. 2004.

Adult habitat & habits


S. warnstorfii, along with S. contortum, is one of the most base demanding Sphagnum species. In Ireland it has been recorded in both upland and lowland situations. It has been recorded from base enriched flushes within habitats that are otherwise base poor.

Habitats may include but are not necessarily limited to;

  • Rich fen and flush (PF1)
  • Transition mire and quaking bog (PF3)
  • Eroding / upland rivers (FW1) Riparian
  • Freshwater marsh (GM1)

Sources: Atherton, I., Bosanquet, S., Lawley, M.,  2010; Rodwell, J.S. (ed.) 1991; Hill, M.O. et al 1992; Lockhart, N. et al 2012a; Fossitt, J.A. 2001.


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 capsule which is borne on a pseudopodium produced from tissue of the gametophyte.

Fertilization of female gametes by male gametes produces the diploid sporophyte. Meiosis of spore mother cells produce haploid spores, which are disseminated when the capsule opens. Spores germinate into a filamentous 'protonema' which will eventually produce the familiar moss gametophyte.

Sources: Porley, R. Hodgetts N. 2005.

Sphagnum species can also spread vegetatively through the development of new stems from branches and may also spread via plant fragments.

Life cycle

Threats faced

In the Article 17 Habitats Directive reporting for the period 2007-2012 no current threats were listed for this species. In that reporting period the named Sphagnum species of the Habitats Directive occurring in Ireland were given an 'Overall Assessment of Conservation Status' of 'Inadequate' due to;

  • 'The poor conservation status of the peatland habitats within which the majority of Sphagnum species occur'.
Source: NPWS 2013.

In Rare and Threatened Bryophytes of Ireland threats to this species are related to land reclamation and include;

  • Drainage of rich fen sites
  • Eutrophication of rich fen sites.
Source: Lockhart, N. et al 2012a.

Conservation actions

In the Article 17 Habitats Directive reporting for the period 2007-2012 no Conservation Measures in place or in the process of being implemented during the period were listed for this species.

Source: NPWS 2013.

In Rare and Threatened Bryophytes of Ireland the suggested conservation action is;

  • Protection from damage caused by drainage.
Source: Lockhart, N. et al 2012a.


World distribution(GBIF)

Recorded in Ireland and Britain, the west of northern Europe and scattered mountainous and lowland regions of central and southern Europe.Records also from the North America as well as Japan, Iceland, Greenland and Svalbard. 

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

Very few recorded sites in Ireland. Overall, records would suggested a north western distribution although recent and hsitorical records exist for the south of the island.

Distribution frequency in Ireland

Temporal change

Records submitted to Data Centre in 2023

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

How can you help

The National Biodiversity Data Centre is trying to improve our knowledge of the distribution of Sphagnum warnstorfii in Ireland. Should you observe this species, please submit sightings to add to the database. Detailed observations will assist us gaining a better insight into where the species 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.

Frey, W.,  Frahm, J.P., Fischer E., and Lobin W. 2006.  The Liverworts, Mosses and Ferns of Europe. Harley Books, Colchester.

Hill, M.O., Preston C.D., and Smith A.J.E., 1992. Atlas of the Bryophytes of Britain and Ireland Vol. 2 Mosses (except Diplolepideae). Harley Books, Colchester.

Holyoak, D. T. (ed.). 2003. The distribution of bryophytes in Ireland: An annotated review of the occurrence of liverworts and mosses in the Irish vice-counties baseed mainly on the records of the British Bryological Society. Broadleaf Books, Wales.

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.

Lockhart, N., Hodgetts, N. & Holyoak, D. (2012a) Rare and Threatened Bryophytes of Ireland. National Museums of Northern Ireland.

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

Rodwell, J.S. (ed.) 1991. British Plant Communities Vol.2 Mires and Heaths.Cambridge University Press.

Smith, A.J.E. 2004. The Moss Flora of Britain. Cambridge University Press.

The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 21 November 2014