Cypress-leaved Plait-moss.
I’m saying “probably” because this is one of those mosses which seems to come in many guises, some of which may be other species (such as Hypnum jutlandicum).
However, it seems to fulfill all the criteria for Hypnum cupressiforme, with irregular branching shoots and strongly curved leaves. The leaves are like little sloth claws, curved in on themselves.
I found it (March) covering some boulders beside the Tay, then later in woodland (Kiel’s Den):
The colour is golden-green. I didn’t find any young lidded capsules, which might have helped with ID.
The leaves are supposed to have well-defined patches of small greenish cells at the basal angles. Well, the leaves are so tiny that trying to get one under the microscope was quite a challenge. Fiddly little things. However, eventually I got one there and saw two greenish patches. Decided to be content with that.
Not one of my favourite mosses so far. (Although I do like the little furry claws.)
Updated Sept 2019
Found it with capsules at Tentsmuir, growing on a fallen tree. Looking furry.
The young capsules have a long thin point, which gives way to a lid with a definite beak (not just a short stub like Hypnum andoi).
Under the microscope, I could see the characteristic patches of green cells at the bottom corners of the leaf. (No pic.)
I then saw it after rain, when it had a swollen, less furry look that made me think of Pseudoscleropodium purum.
However, the book reminded me that Pseudoscleropodium purum rarely has capsules. And the leaves are quite different, close up.
Learning about Mosses 