Sphagnum affine | Imbricate 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 (D2)
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 2014.2.

Legal status

Protected by the following legal instruments:

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

Native status


Species Biology


All members of the Sphagnum genus are distinguished from other moss species by the combination of the following characteristics;

  • The absence of rhizoids in the gametophyte, and the presence of goups of spreading and / or pendent branches (these groups referred to as fascicles) arranged at intervals along the main stem.
  • As well as chlorophyllose cells 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.
  • The top end of the plant, where new fascicles are formed, contain many young compact fascicles which give Sphagnum species a distintive 'mop-head' look. This terminal head is termed a capitulum.
  • Rather than the seta (stalk) seen in other mosses, in Sphagnum species the spore bearing capsule is borne on a pseudopodium.
  • The lack of a leaf mid-rib or 'costa'.
Sphangnum affine is one of a group of Sphagnum species (Section Sphagnum) in which the stem has a wide outer cortex to inner pith ratio (outer cortex occupies about 1/3 or more of the diameter).

  • Section Sphagnum species plants, in well-lit, good growing conditions will measure over 2.5cm in diameter, including fascicles.
  • The branch leaves in Section Sphagnum are egg shaped, noticably concave with blunt, hooded apices.
  • The stem leaves are rather tongue shaped.
  • Branch leaves are most often over 1mm wide.

Within this group Sphagnum affine never has red or pink colouration in leaves. It's colour can vary from yellowish-green to ochre or dull brown.

  • Shoots to 15cms long.

  • The branches are relatively short with pointed ends. Two pendent branches per fascicle, two (sometimes three) spreading branches.
  • The habit of this species is to form low, moderately compact hummocks, or carpets.

  • In Britain Sphagnum affine tends to inhabit slightly more basic situations than the related Sphagnum austinii, however in Ireland that habitat separation does not appear to be as clear.
In the field, and depending on growing conditions and time of year, Sphagnum affine could be confused with other species (particularly Sphagnum papillosum and Sphagnum palustre) and microscopic examination will be necessary. Examination should focus on such characteristics as the presence of comb-fibrils on the inner wall of both branch leaf cells and stem leaf cells and the triangular shape of chlorocysts in the branch leaves.

There are only three post 1950 records for this species in th Republic of Ireland and one 19th century record in Northern Ireland. It is only relatively recently regared as a species rather than a subspecies. It may be under-recorded, however it is likely quite rare in Ireland.

Sources: Atherton, I., Bosanquet, S., Lawley, M.,  2010; Lockhart, N., Hodgetts, N. & Holyoak, D. 2012a; Frey, W. et 2006; Smith, A.J.E. 2004


Habitats may include but are not necessarily limited to;

  • Cutover Bog (PB4)
Source: Lockhart, N., Hodgetts, N. & Holyoak, D. 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.

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.

The species account for Sphagnum affine in 'Rare and Threatened Bryophytes of Ireland' indicates that the following two activities would be considered as major threats to this species, particularly with regard to its current known locations;

  • Drainage
  • Afforestation
Source: Lockhart, N., Hodgetts N., and Holyoak D., 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.

The species account for Sphagnum affine in 'Rare and Threatened Bryophytes of Ireland' suggests the following Conservation Actions;

  • Monitoring of known populations.
  • Protect known populations from drainage and afforestation.
Source: Lockhart, N., Hodgetts N., and Holyoak D., 2012a.


World distribution(GBIF)

In Europe records are concentrated in Norway, Sweden and Britain with records also from Ireland, Iceland, Denmark, and the Netherlands.It is also recorded in eastern North America.

It has also been recorded in the Azores, the Czech Republic, Finland, Switzerland and Asian Russia (Lockhart, N. et al, 2012a).

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

Records post 1950 are from three 10km squares. Two of these are contiguous and located in Killarney National Park in Kerry, the third in Co. Galway in the Twelve Bens / Garraun Complex S.A.C.

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 affine 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.

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.

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

The IUCN Red List of Threatened Species. Version 2014.2. <>. Downloaded on 13 November 2014.