Fissidens celticus, also known by its common name Welsh pocket-moss, is a species of moss in the family Fissidentaceae.

[6] Fissidens celticus can be distinguished from F. exilis by its longer shoots, its greater number of leaves and its lack of capsules.

[4] Fissidens celticus grows on shaded soil banks near woodland streams, especially on bare, compact patches eroded by floodwater.

[1] The species holotype was from Hustyn Wood, St Breock, Cornwall,[6] and it is common throughout the western parts of the United Kingdom.

[22] It was found in Bozyazı, Mersin Province, associating with Bartramia stricta, Bryum dichotomum, Didymodon tophaceus, Targionia hypophylla and Timmiella barbuloides.