Northern Ireland's Priority Species

Lycopodiella inundata – marsh clubmoss


Distribution map

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Lycopodiella inundata (L.) Holub
Family: Lycopodiaceae

Marsh clubmoss is a small perennial low-growing and insignificant-looking plant found on bare peat in heath flooded in winter. It is known only from one site in Northern Ireland where it was first found in 1964 and last seen in 2005. In Ireland generally, it is a rare species, recorded from only seventeen 10 x 10km squares, in six of which it has not been seen since before 1970. It has a discontinuous distribution around the northern hemisphere with Europe and eastern North America being the principal regions of occurrence. It has declined considerably in much of its European range.

In brief

  • Within Northern Ireland, restricted to Peatlands Park, County Armagh

  • Grows on bare peat subject to seasonal flooding

  • Best seen when the ‘cones’ are produced (June onwards)

  • A UK Priority Species which is rare and declining

  • Threatened by habitat changes, especially development of closed, scrubby vegetation and loss of bare peat.

Species description
Marsh clubmoss is a small, bright green plant with prostrate, creeping shoots, rooting in the peat along their full length. The shoots are covered by tiny ‘spiky’ leaves which are curved upwards on the prostrate shoots. The spore-bearing bodies or ‘cones’ appear in June – July, maturing in late autumn; these are borne on vertical shoots which are no more than about 8cms tall at the most.

Life cycle
Marsh clubmoss is a pteridophyte (a group including the ferns, horsetails and other clubmosses). The plant is a non-sexual sporophyte, that is, it produces spores in the ‘cones’ which, in theory, can germinate to produce a small and insignificant sexual stage known as the gametophyte, whose development is probably dependent on an associated fungus. At this stage male and female organs are formed, producing sperm and eggs. Fertilised eggs can grow into the mature sporophyte. This life cycle, involving an alternation of sexual and non-sexual generations, is typical of other pteridophytes. However, the gametophyte stage has never been directly observed in British or Irish populations. It seems likely that much of the local propagation of the plant is by vegetative growth and division or fragmentation of individual shoots. Winter die-back of the plants to just a short length of shoot with a growing-tip is normal.

Similar species
The marsh clubmoss bears some resemblance to other species of clubmoss, especially the much commoner fir clubmoss (Huperzia selago), but that species lacks the creeping shoots and does not have distinct ‘cones’ like marsh clubmoss. The stag’s horn clubmoss (Lycopodium clavatum) is also somewhat similar but is more robust and its upright shoots are very slender below the cones.

How to see this species
The plant grows on a wet heath on the site of the drained Annagarriff Lake in Peatlands Park, County Armagh. It should be searched for on patches of bare peat in late summer or autumn, and when the site is not flooded. You should inform staff at the Peatlands Park if you wish to search for this plant.

Current status
Confined to a single site where its abundance has declined over recent years. It is protected under the Wildlife Order (NI) 1985. The site is designated an ASSI and Special Area of Conservation.

Why is this species a priority in Northern Ireland?

  • Listed as a UK Priority Species

  • It is rare and declining.

Threats/Causes of decline
The number of plants at the site has declined considerably over the past ten years according to local staff of the Peatlands Park. This appears to be associated with a loss of extensive areas of bare peat and competition with other plants. Any future artificial changes to the general level of the water table at the site could adversely affect the species.

Conservation of this species

Current action
There is a UK Species Action Plan for marsh clubmoss published in 1998. The lead partner is Plantlife.

  • The single site occurs within the Peatland Park and is managed as a nature reserve by EHS

  • The Peatlands is also designated as both an SACand ASSI

  • It is subject to frequent monitoring by EHS and others.

Proposed objectives/actions

  • Maintain viable population

  • Establish appropriate management of the species’ habitat

  • Achieve an increase of 20 per cent in population size of this species

  • Carry out further surveys for the species in suitable areas in the vicinity of the site

  • Assess the feasibility of supporting the conservation of this species through an ex-situ programme

  • Ensure that the needs of this species are taken into consideration when implementing the Lowland Raised Bog Habitat Action Plan.

What you can do
Records of sightings of this species are important, especially if you find it in a new site outside the Annagarriff area. Send any records to either Botanical Society of the British Isles, c/o Botany Department, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU or to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU, Tel: 028 9039 5256, [at] Alternatively, contact the staff of Peatlands Park, Tel: 028 3885 1102.

Further information

UK Species action plan for Lycopodiella inundata

Plantlife – information on marsh clubmoss and the species action plan

UK Species action plan for Lycopodiella inundata

Flora of Northern Ireland

Jermy, C. and Camus, J. (1991). The Illustrated Field Guide to Ferns and Allied Plants of the British Isles. Natural History Museum, London.

Preston, C.D., Pearman, D.A. and Dines, T.D. (2002). New Atlas of the British & Irish Flora. Oxford University Press/DEFRA

Text written by:
Paul Hackney