Thursday, 31 March 2016

Leucobryum in Crynant

Prompted by Barry's last post I dug out a specimen I took from a Leucobryum colony H and I found in peaty Molinia heathland at the edge of an oak-birch woodland. There was just one neat colony, at the side of a path, which looked dead right for L. glaucum to me at the time.

Leucobryum in Crynant (photo taken in July 2014)

L. glaucum is more likely in this sort of habitat than L. juniperoideum (I thought). I remember checking the leaves and convincing myself that the lower, wide portion was at least as long as the narrow upper part. I recorded L. glaucum. When I revisited my specimens today I found leaves that would fit descriptions of either or both species (re: Barry's comments in last post), some with very long narrow upper portions that I shouldn't have ignored at the time. So, I cut some leaf costa sections from the lower part of the leaf and they show the 2-cell thick structure that is indicative of L. juniperoideum

Now, when I look at my original photos the colonies do look more lax than the typical compact cushions formed by L. glaucum, of which there are classic examples in the lower Hepste valley below Scwd yr Eira. Mea culpa.


  1. The value of a voucher - seems there's some habitat overlap in our area, so leaf sections might be worth adopting as standard where there's any ambiguity. It's not a common genus so worth the extra bit of effort.

  2. Hi, I hope you don't mind a non-South-Walian (actually a North Walian in Scottish exile) intruding on your excellent blog, but I wanted to acknowledge this post, and other linked ones, for having put me on the right track re Leucobryum ID. Where I live, L. glaucum is really the only option, but I was struggling with some specimens collected in France that seemed to have highly variable leaf shape. Using Smith, I was getting nowhere, then I saw the above leaf cross-section image on Google, and bingo - problem solved. My French ones are also L. glaucum, even though smaller and finer than Isle of Lewis plants, and I could easily have convinced myself that they were L. juniperoideum.

  3. Constructive comments are always welcome Tristan - glad you found the blog helpful.