Species of the Month April 2020


Grey-cushioned Grimmia Grimmia pulvinata


This common moss species can be found in most gardens. It tolerates moderate pollution, so is a characteristic urban and suburban species, growing on wall tops, mortar, tombstones, asbestos roofs and concrete, and is a typical member of the wall community. The neat cushions on wall tops have earned it the alternative common name of 'Hedgehog Moss'.

This is the commonest British Grimmia, and forms round, almost furry, grey cushions about 1 to 2 cm tall. The narrow leaves are 3 to 4 mm long, nerved to the tip, with recurved margins. An important character is the leaf tip, which is abruptly contracted into a long hair point, which may be almost as long as the leaf blade. Oval capsules usually abound, bending back into the cushion on an arching seta (note, however, that when old and dry, the seta straightens and the capsule is held erect); the lid of the capsule has a long beak. In moist conditions, cushions appear dark green, the densely arranged leaves spread away from the stem and the hair points are only moderately conspicuous. When dry, the leaves fold together, with the result that the long, silvery hair points loosely entwine and are then particularly eye-catching.

It is widespread throughout Wales, but we only have 660 records in the SEWBReC database (view the Wales wide distribution on Aderyn).

You can see more images of Grey-cushioned Grimmia on Naturespot (where much of the above text is taken from), and also on this excellent species account [pdf] from "Mosses and Liverworts of Britain and Ireland: a field guide". Accounts for other species can be found on the British Bryological Society website. If you are unsure of species identification, please share a photo with SEWBReC and we will pass it on to an expert.

If you spot Grey-cushioned Grimmia during March (or at any other time of year), please send us the record, ideally via our Species of the Month form on SEWBReCORD (nb. you will need to be signed into SEWBReCORD to use this link). Instructions on how to submit records are available here.

*COVID 19 note: we do not advocate unnecessary travel for recording purposes during this time of crisis. We still encourage you to look for the Species of the Month, but please do so in a safe, socially distant and local manner, e.g. concentrating on your own garden.*