Ptychostomum cyclophyllum
Ptychostomum cyclophyllum, round-leaved bryum, is a species of moss belonging to the family Bryaceae.
It is native to the Northern Hemisphere. It grows in wetlands and along streams.
In the UK, it has only been found to occur naturally in one location. In 2025, efforts were made to establish it in the muddy waters of two reservoirs in Scotland, at Loch Coulter and Threipmuir Reservoir.