The Silky Wall Feather-Moss (Homalothecium sericeum).

The bryophytes - mosses, liverworts and hornworts - are leafy or flattened green plants that have been around for at least 400 million years. They are abundant in shady or damp places such as forests, alongside rivers and in bogs. Although often reliant on a constant water supply, some species are more tolerant to drying out and can be found on sunny rocks and other dry places where they can be important colonisers. There are 1000 species in Britain, with around three quarters of these found in Wales due to the diverse habitats found in this country.

This diversity in bryophytes is represented in the bryophyte herbarium at National Museum Wales. Our bryophyte collections of around 280,000 specimens are second only in size to the Natural History Museum in London. Over half of our specimens are from Wales but many come from all over the world, from New Zealand and Afghanistan to Norway and Argentina.

The National Museum Wales herbarium has gained much value from the inclusion of the British Bryological Society’s UK herbarium and from many world renowned British Bryologists herbaria such as P.W. Richards, F. Rose and E.C. Wallace. » A history of the herbarium

A particularly interesting part of the collection are the 3D bryophyte slides made by H.L.K. Whitehouse. They are one of only two sets made by him in the world and can be viewed here. National Museum Wales also holds the herbarium of H.L.K. Whitehouse of some 10,000 bryophyte specimens.

Detailed information about the bryophyte collections can be found in online catalogues.

Specimen Storage and Conservation

Birch drawers house the bryophyte specimens within purpose-built steel compactor units. An integrated approach to pest management is taken to reduce pest numbers by minimising the elements essential for pest survival and limiting damage to specimens. Thus, in the herbarium, we try to achieve a relative humidity of 50%RH, +/- 5% and a temperature of 20°C, +/-2°C.

A regular vacuuming regime reduces dust and debris in the herbarium that could harbour herbarium pests. The majority of herbarium pests are further controlled by periodically freezing specimens down to -20°C or below for five days. The bryophyte collections are frozen on a rotational basis with all in-coming material frozen on entry to National Museum Wales.

Specimens enter the museum in a range of packet types, some requiring little work and others requiring more detailed curation. Curation entails placing the specimen and original packet data into an archival polyester envelope. The static properties of polyester prevents loss of material and balances the acidity of the specimen and its environment. The polyester also retards degradation of acid paper thus preserving original script.

The envelope is then placed into a packet which is pre-printed with the specimen data. The packet is folded from an A4 sheet of acid-free 100% cotton archival paper. Cotton is less vulnerable to pest damage and more resistant to degradation than paper made from wood pulp.