Dicranum fuscescens is a relatively common moss of hilly districts and able to thrive in relatively high, cold situations. In the field it is a similar size to Dicranum scoparium, but is a darker plant, with narrower leaves and wispier-looking leaf apices. Like the majority of Dicranum species it is a calcifuge and restricted to acid substrates.
When D. fuscescens has mature capsules, they are inclined to curved and strongly furrowed when dry. Like many other species though, the shape of the capsule can change over time, so it’s sensible to check leaf characters too.
In the British Isles it is probably most likely to be confused with the scarcer, hyperoceanic D. scottianum, although that can be a smaller plant (not a reliable character!) and when mature (but not old) capsules are present they are usually erect or slightly curved.
Two useful microscopic features of the upper leaf of D. fuscescens that deserve to be better known are (i) scattered mamillae on the abaxial side i.e., underside and (ii) a strongly toothed apex. D. scottianum has neither.Read the Field Guide account