Identification notes
This is one of a number of liverworts that usually grow over or in Sphagnum, Leucobryum or wet peat. Sometimes it can grow in thin patches on the surface, but often just as straggling shoots growing within a Sphagnum hummock, close to the surface. It is a small plant, with shoots up to 1.5 mm wide, so often appears as fine strands when teasing apart a handful of Sphagnum. When growing in patches on the surface the gemmae on the shoot apices draw the attention, but often these are absent. Quite often it grows mixed with other bog liverworts.
The leaves are often triangular with a falcate tendency which is quite characteristic and a good pointer. Often, they are quite distant on the stem, so this can be seen clearly. The apex tends to be subacute but is occasionally bifid. C.fissa can grow in similar habitats and small forms can look quite similar, so it is worth checking microscopically.
Fresh material under the microscope shows eight or so oil bodies per cell, which are simple or few-segmented. This is an important character to separate it from C.fissa which has oil bodies with multiple segments. The rhizoids arise from an oval area at the base of the underleaf, unlike the linear area in C.fissa, which also has decurrent underleaves. The midleaf cells tend to be isodiametric and are usually less than 40μ long.
Calypogeia suecica is similar but grows on rotting wood.
Read the Field Guide account
