Identification notes

This underwhelming and not particularly common plant is found in damp shaded calcareous habitats, usually manmade, including damp brickwork and masonry, kept moist by the seepage of water. It forms small watery-green cushions that are usually encrusted with lime deposits. The leaves are often flexuose and are spreading/recurved. The leaf base, visible with a hand lens if you can peel off a leaf, is composed of large hyaline cells. Under the microscope the basal marginal cells are narrowly rectangular. It produces protonemal gemmae.

It has a similar colour and tendency to become encrusted as Eucladium verticillatum, but the leaves are longer and more flexuouse and the basal cells are different. Didymodon sinuosus has similar shaped leaves and grows on damp brickwork but it is a larger and darker plant, usually without the lime encrustation. Perhaps the most common lookalike is a decomposing cushion of Didymodon vinealis.

Distribution in Great Britain and Ireland

This has a south-eastern distribution, with a concentration of records in Cambridgeshire, where generations of bryologists from Harold Whitehouse onwards have become particularly skilled in finding it.