Identification notes
Note that the old var. perigoniale has now been promoted to a full species, its Field Guide and 2014 Atlas pages have been moved to the Polytrichum perigoniale page. This page refers to the old var. commune only.
When well-grown, P. commune is one of our largest mosses, with individual stems reaching up to 40 cm long. In favoured habitats, e.g. mires, blanket bog, flushes, poor fen and wet heath (often with Sphagnum species), its hummocks can easily reach half a metre wide and then it is easily recognised.
Carefully strip off a stem leaf and its pale sheathing base is glossy, a point of distinction from P. formosum whose leaf base is not glossy. However, this character sounds more straightforward than it often is, and a transverse section of the leaf (above the base) to view the shape of the uppermost cells of the lamellae overlying the nerve is a more reliable means of identification. Fortunately, cutting leaf sections of Polytrichum species is not difficult with a sharp razorblade as they are relatively rigid.
Read the Field Guide account
