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I think there are both Thuidium and Hylocomium here! The Hylocomium is on the right.
I think, Nick, if you look at this again, you will see that the main plant has orange stems under the leaves. Yes, no dispute about the older plantlet to the right, but I maintain my view that everything in the photo is Hylocomium.
[And yes, I am aware that the stem of rather old Thuidium can discolour red, but this is healthy material here.]
I bow to Dr Martha Newton who surveyed our Community woodlands and passed on an incredible amount of knowledge to me about mosses in the few days I spent with her in the field. The photos are mine.
Sorry Alan, but I have to stick to my guns here! The one on the left most definitely has a Thuidium-like texture, and the orange coloration is by no means convincing!
I respect your views and experience, but it is amazing how often these "Thuidium-like" plants are actually Hylocomium once under the microscope. To me this is still Hylocomium pretending to be Thuidium.
I have checked Dr Martha Newton's report.
"Bryophyte survey: Windyhills Trust Reserve.
A total of 99 taxa was recorded consisting of 76 mosses and 23 liverworts.
Hylocomium splendens and Thuidium tamariscinum are both recorded on the site so there is a chance that both species are in the picture.
Lat/Lng: 57.44594, -2.33318
OS grid ref: NJ801395