Hamatocaulis vernicosus | Varnished Hook-moss



Conservation status

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

Source: NPWS 2013.

IUCN Conservation Status
Ireland (1)
Near Threatened
Europe (2)Not evaluated*
Global (2)
Not evaluated

*Although not published separately, an evaluation of 'Vulnerable' 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., 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 II
  • Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention) Appendix I
  • Wildlife Act (1976)
  • Flora Protection Order (1999)*
  • Wildlife (Amendment) Act (2000).

*Note that Hamatocaulis vernicosus is listed as Drepanocladus vernicosus in the Flora Protection Order (1999).

Native status


Species Biology


Pleurocarpus (branching) moss . Shoot-tip has hooked appearance. Branches are generally held at ninety degrees to stem. Overall a medium-sized to robust species. Habit varies from upright to sprawling. Leaves 2-3mm in length. Leaf veins extend to between 50% to 75% the length of the leaf.  Leaves taper gradually from a broad base to a point that is strongly recurved.TLeaves are pleated, their bases often streaked red which lends the appearance of a reddish hue to branches. The redness at leaf base (not always present) can be useful as a guide to identification in the species most usual habitats.Capsules rare in Ireland.

Sources: Lockhart, N.,Hodgetts N., and Holyoak D., 2012a; British Bryological Society 2010.


Transition mires, and mineral rich (but not necessarily calcareous) flushes in bogs and fens.

Habitats may include but are not necessarily limited to;

  • Transition mire and quaking bog (PF3)
  • Rich fen and flush (PF1)
  • Poor fen and flush (PF2)
  • Upland blanket bog (PB2)
  • Lowland blanket bog (PB3)
  • Cutover bog (PB4)
  • Eroding blanket bog (PB5)

Sources: Lockhart, N.,Hodgetts N., and Holyoak D., 2012a; British Bryological Society 2010; NPWS 2013; 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 short lived seta (stalk) and capsule.

In Hamatocaulis vernicosus 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.

In Ireland the sporophyte generation of Hamatocaulis vernicosus is rarely, if ever, produced. Other non-sexual methods of reproduction apart from by fragments are not known.

Sources: Porley, R. Hodgetts N. 2005; Lockhart, N., Hodgetts N., Holyoak D., 2012a;Atherton, I., Bosanquet, S., Lawley, M., 2010

Threats faced

In the Article 17 Habitats Directive reporting for the period 2007-2012 no threats or pressures were identified at the Hamatocaulis vernicosus sites examined.

Source: NPWS 2013.

The species account for Hamatocaulis vernicosus in Lockhart, N., Hodgetts N., and Holyoak D., 2012a indicates that the following have contributed to the loss of populations in the past, and that these activities have the potential to threaten populations still;

  • large scale peat extraction
  • afforestation
  • drainage
  • eutrophication
Source: Lockhart, N.,Hodgetts N., and Holyoak D., 2012a.

Conservation actions

In the Article 17 Habitats Directive reporting for the period 2007-2012 Conservation Measures in place or being implemented during the period consisted of;

  • continued legal protection of the species and its habitats inside and outside of Natura 2000 sites.

Source: NPWS 2013.

In the Irish Bryophyte Red List 2012 Conservation Actions needed are listed as;

  • Ex-situ Conservation 
  • Awareness and Communications

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


World distribution(GBIF)

The species appears to have a widespread but relatively scattered distribution. Heavier densities are found throughout Scandinavia, and there are a few locations through Britain, Ireland and mainland Europe. It appears to occur at low densities throughout North America and there are records from the north west of South America.

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, apart from southwest, but scarce.

Temporal change

Records submitted to Data Centre in 2022

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 Hamatocaulis vernicosus in Ireland. Should you observe the species, please submit sightings to add to the database. Detailed observations will help us gain a better insight into where Hamatocaulis vernicosus is most abundant in Ireland and we might also detect regional variations in distribution. 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.

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

The IUCN Red List of Threatened Species. Version 2014.2. <>. Downloaded on 25 September 2014.

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