Oblong woodsia (Woodsia ilvensis)

Oblong woodsia
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Oblong woodsia fact file

Oblong woodsia description


This fern, thought to be Britain's rarest, is small in comparison with other members of its class. The variable-length leaves are a mid-green and their undersides are very hairy. The reddish-brown stalks are also hairy and covered in scales.

Leaf length: 4-20 cm (variable)

Oblong woodsia biology

Like all ferns, the oblong woodsia reproduces by producing spores instead of seeds. These spores develop a small green disc called a prothallus, which in turn produces the gametes. The gametes have to swim through water to reach each other in order to fuse and produce a new spore-bearing plant. The thinnest of films will do, but this reliance on water means the fern is limited to a habitat that remains wet or moist for at least part of the year.


Oblong woodsia range

Oblong woodsia is common in Sweden and Norway and scattered across central Europe and Iceland. In the UK it is limited to five 10 km squares, with the largest colony in the Lake District and other populations in Scotland and Wales.

You can view distribution information for this species at the National Biodiversity Network Atlas.

Oblong woodsia habitat

This is a plant of tree-less, rocky habitats above 350 m, found growing in crevices in rock or on ledges in Britain, but in Europe it is found in woodland and even coastal areas.


Oblong woodsia status

Classified as Endangered in the UK.


Oblong woodsia threats

Like the Killarney fern, oblong woodsia was a victim of the Victorian craze for collecting. It used to be thought that over-collecting was responsible for the plant's seeming inability to reproduce readily in the wild through a reduction in genetic viability. This is now believed to be untrue. The species is on the edge of its range in the UK and it is thought that the greatest threat to its survival here is climate change. With such isolated populations, there is little chance of the fern migrating to new sites should temperatures rise.


Oblong woodsia conservation

The oblong woodsia is listed in the UK Biodiversity Action Plans, and included in English Nature's Species Recovery Programme and Scottish Natural Heritage's Species Action Programme. All known populations are protected within Sites of Special Scientific Interest (SSSIs) and three are with National Nature Reserves (NNRs).

Attempts have begun to re-establish ex-situ populations. The Royal Botanic Gardens, Edinburgh, have grown sporelings collected under license from most of the wild sites in 1996. Plants have been reintroduced in Teesdale in the north of England, and in the southern uplands of Scotland, and these are being monitored each year to check the progress of the species recovery.

The UK Biodiversity Action Plan for this species is available at UK BAP.
There may be further information about this species available via the National Biodiversity Network Atlas.

Find out more

See also Royal Botanic Gardens, Edinburgh:



This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact: arkive@wildscreen.org.uk


A group of organisms living together, individuals in the group are not physiologically connected and may not be related, such as a colony of birds. Another meaning refers to organisms, such as bryozoans, which are composed of numerous genetically identical modules (also referred to as zooids or 'individuals'), which are produced by budding and remain physiologically connected.
Measures to conserve a species or habitat that occur outside of the natural range of the species. E.g. in zoos or botanical gardens.
Microscopic particles involved in both dispersal and reproduction. They comprise a single or group of unspecialised cells and do not contain an embryo, as do seeds.



Image credit

Oblong woodsia  
Oblong woodsia

© Andrew N. Gagg

Andrew N. Gagg
'Town House Two'
Fordbank Court
Henwick Road
United Kingdom
Tel: +44 (0) 190 574 8515


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