Aquatic plants

One of the most notable aquatic plants in the Yorkshire Dales National Park is the Yorkshire feather moss.

Taxonomic information

Common Name: Yorkshire feather moss

Latin Name: Thamnobryum cataractarum

Family: Thamnobryaceae

Description

Yorkshire Feather Moss.
Photograph by Nick Hodgetts.

Yorkshire feather moss is the subject of a national and local Species Action Plan. This aquatic species grows below the water level on gritstone rock, in a base-rich stream fed by water running off areas of surrounding limestone. It is a species relatively new to science, having only been discovered by bryologists Hodgetts and Blockeel in a deep ravine in the Ingleborough area of the Yorkshire Dales National Park in September 1991. Research has shown that it is most closely related to Thamnobryum fernandesii, a moss that is endemic to Madeira.

The genus Thamnobryum contains many species that have a distribution which is restricted to a very small geographical area. Therefore, it was expected that T. cataractarum would not be found at many locations away from the discovery site. Comprehensive survey work was carried out at the one known site and in the surrounding areas in 2005 to determine the true status of this species.

At the discovery site the river runs through a deep ravine making it a particularly difficult area to survey. However, despite these problems, the moss was found at the majority of locations where it was possible to access the river. The results of this survey showed that Yorkshire feather moss is frequent to locally abundant along a stretch of river approximately 1km long. However, no specimens of Yorkshire feather moss were found at any location outside of the ravine. Whilst there may well be some as yet undiscovered locations where this species grows, it is looking increasingly likely that the only site in the world for this species is a short stretch of river in the Ingleborough area of the Yorkshire Dales National Park.

Links:

Yorkshire Dales National Park Authority, 2006. A Summary Report Of Yorkshire Feather-Moss Thamnobryum cataractarum Survey Work In The Yorkshire Dales National Park 2005. Yorkshire Dales National Park Authority Conservation Research & Monitoring Reports No.3.

Yorkshire Feather Moss Local Species Action Plan

Rivers and Streams

Websites:

Yorkshire Feather Moss National Species Action Plan

Other sources of information:

Hodgetts, N.G. and Blockeel, T.L. (1992) Thamnobryum cataractarum, a new species from Yorkshire, with observations on T. angustifolium and T. fernandesii. Journal of Bryology  vol 17, pp251–262.

Orton et al. (2000) A guide to commoner water plants Field Studies Council. Fold-out chart available from the Field Studies Council or Tel: 01743 852140.