Tuesday, 1 May 2018

Puncheston Common

Following our weekend twitch to see the Green Heron in the garden pond of Simon Hart MP, we headed up to Goodwick to look for the Black Guillemots. On the way I managed to convince the gang that Puncheston Common would be a good place to stop and decant our flasks and have a 15-20 minute break, hopefully this giving me enough time to relocate one of Sam's Hamatocaulis vernicosus sites. We stopped by the Waldo Williams plaque and after wandering around for 10 minutes I finally found some healthy patches of Hamatocaulis in very soggy ground surrounding the willows shown centre-right in the above photo. Capsules were reasonably frequent in one patch, which may be of note given the text books all state capsules are rare. The richer orange hues and thicker stems made plants stand out in comparison to Sarmentypnum exannulatum, which was much more frequent at the site. Now it's on my radar, I'd love to find this in Gower.

An unexpected bonus was a small but healthy population of Sphagnum platyphyllum at the same locality (photos below), though with warnings of how denticulatum can appear almost identical I'd welcome comments on my id. The texts I have indicate the double layer of cortical cells rule out this potential confusion with denticulatum, plus all the other key characters fit perfectly. The centre of the colony had rather well grown material (the darker of the images below), which looked quite different to the straggly big-budded smaller shoots, but microscopically they were identical. If correct this would represent a westwards extension to the population.

Other species noted at this wonderfully rich site included Anagallis tenella, Breutelia chrysocoma, Calliergon cordifolium, Drosera rotundifolia, Leucobryum glaucum, Menyanthes trifoliata, Narthecium ossifragum, Pedicularis sylvatica, Plagiothecium denticulatum var. denticulatum, Sphagnum squarrosum, S. tenellum, S. teres, Straminergon stramineum, Viola palustris and Wahlenbergia hederacea. This richness contrasts strongly with a lot superficially similar, but much poorer sites in Gower, which makes me wonder how much of an impact burning has on bryophytes, especially given how regular burning is carried out on the commons these days. I wonder if the Pembroskeshire commons are burned less frequently, or is the oceanic effect a bigger factor?

One final note on Leucobryum, it's worth pointing out that the first leaf section I looked at initially made me believe that the plants on the common were juniperoideum and it's only as I was expecting glaucum that I double checked. I'm sure you all do anyway, but do make sure that you cut leaf sections from the basal part of the leaf only. Both images below are from he same L. glaucum plant.

One of the more productive 15 mins in the field I've spent looking at bryophytes, although it was backed up by an hour or so of microscope work!


  1. Nice!

    I visit the site every September to do Marsh Frit web counts, but have to confess to having ignored the bryos (always in a hurry...). Maybe I'll make a bit of time to have a look at them this year!

    The common does get burnt regularly, in most if not all years, though there are many really wet bits that avoid the burn.

  2. Looks like part of the common had been cut too, which must require some specialist kit given how boggy it is.

  3. Sorry for the late reply, Barry. Well done on the Sphagnum platyphyllum, which is indeed a good few km west of its Preseli heartland. The common was really rank when I first NVC mapped it, as far as I remember, and the Succisa patches were isolated among tall Molinia. I only have 4 species recorded from there in my VC45 database (!), stemming from the NVC survey, because the Waun-fawr bit of it was quite species-rich.