For obvious reasons I haven't done much riparian recording this winter, but after a couple of almost dry days I thought I'd chance my arm on a lunchtime outing at Peterston-super-Ely (ST0876) today. Just west of the village is an easily accessible riverbank section with several mature trees, and happily the water level was low enough to expose the flood zone mosses.
Most of the expected species were there: Homalia trichomanoides, Cinclidotus fontinaloides and Plagiomnium rostratum (all on alder), Leskea polycarpa (on Sycamore) and a fair sized patch of Mnium marginatum on the silty riverbank. Best of all was a few small tufts of Orthotrichum sprucei on alder roots just above the water's surface. The location is two tetrads west of the St Fagans site for this species, but I'd imagine it will be present in the intervening tetrad too - as well as further upstream on the Ely. The arrow in the photo below shows the location.
Elsewhere there were a few riparian species in their more usual tarmac habitat: Dialytrichia mucronata, Didymodon sinuosus and D. nicholsonii. I searched a flailed hedge for Pylaisia without luck, though just below the regular flail zone was a good range of epiphytes - a habitat I'd not appreciated previously.