F. taxifolius is very common. It is however quite variable in size, although regarded among Fissidens as a medium-sized species. It loves clayey habitats but often confuses people by growing in unexpected places, such as arable fields and in chalk grassland.
Identification in the field is in fact straightforward once you memorise two important diagnostic characters. Although we have many species of Fissidens in Britain and Ireland, a relatively small number (8) lack a leaf border of long, narrow cells and F. taxifolius is by far the commonest of those. And it is the only one in which the nerve is excurrent in a stout cusp. And that’s it!
However, in small or very tatty specimens you can sometimes be fooled into thinking the leaf margins look slightly pale and so potentially bordered. However, the only other Fissidens with a stout excurrent nerve is F. rivularis which always has a very conspicuous, yellowish or yellow-red thickened border, which will immediately rule it out.
F. taxifolius var. pallidicaulis is no longer considered to merit varietal status.Read the Field Guide account