BBS SE meeting, 28 April 2019
Continuing the expansion of recording activity eastwards, this field meeting visited an almost completely unrecorded tetrad just north of Battle, largely in the parish of Netherfield. Sitting on the Ashdown Formation, this tetrad had just a handful of old unlocalised records including Ctenidium molluscum, Dichodontium pellucidum, Hookeria lucens, Hyocomium armoricum, Sciuro-hypnum plumosum and Trichocolea tomentella, which was quite tantalising. Seven of us met at the car park at Ashes Wood in the tetrad to the south and quickly headed into our target area, where we benefitted hugely from the local knowledge of Jacqueline, Judy and Robin.
Starting off with revision and an introduction to the common species for beginners, we also found a nice quantity of Metzgeria consanguinea not far from the entrance to the wood. As we worked our way down the valley the large numbers of Hornbeam were evident, with a huge amount of Eurhynchium striatum on the woodland floor, and good quantities of Tetraphis pellucida on old tree stumps.
Dryopteris aemula (Hay-scented Buckler Fern)
As we neared the stream at the bottom of the valley we stopped to admire the cascades of Dryopteris aemula (Hay-scented Buckler Fern) on the banks, first discovered at this site by our Hastings contingent. Here too Sue found a good quantity of Plagiothecium denticulatum on the bank. Tom subsequently had a look at it as well and noted that “Probably more than half of the leaves are asymmetric, often strongly so. The cells in the decurrences are more prominent too.”
Reaching the stream we immediately found Hyocomium armoricum, a moss with a similar Oceanic distribution as Dryopteris aemula, and with a notable occurrence in ghylls in the High Weald. It could be found all along the section of the stream we surveyed.
It was then time for lunch, so we crossed the stream into the parish of Mountfield to sit in the sun in a nice open part of the wood on some logs. Here, right at our feet, was the now common invasive moss Campylopus introflexus, and Sue also located both Pleuridium subulatum and a Bryum, which Tom later identified as Bryum bornholmense. He observed that:
It has almost untwisted tufts when dry and the leaf shape is widest below the middle – that’s an important step because B. bornholmense has several characters in common with B. capillare. Then the leaf cells are 15 – 20 microns and combined with a strong border. Then it has red tubers with only slightly protuberant cells and these are on medium to long rhizoids. They weren’t too difficult to find and, apart from B. capillare and close allies, the wide cells, strong border and red tubers point to B. bornholmense or B. rubens. The less-protuberant tubers on longer rhizoids suggest B. bornholmense and then you measure the width of the nerve at the base of the leaf and 80 – 100 microns on mature leaves helps confirm B. bornholmense. I notice it was on sandy soil and this is primarily a heathland species.
Tuber and leaf base of Bryum bornholmense. Photo: Tom Ottley
Hookeria lucens
After lunch we were back in and around the stream, finding a few small patches of Scapania undulata on the occasional stones in the water, and a large moss- and liverwort-laden bank had a good patch of Hookeria lucens growing on it. Below it, on one stone in the stream were a few stems of what at first sight looked like Hygrohypnum luridum, though they turned out to be rather scrappy bits of Hyocomium armoricum.
Bank with Hookeria lucens
Crossing back over the stream again, an iron-rich flush was rich in Sphagnum palustre and Sphagnum denticulatum, together with some Brachythecium rivulare. S. palustre is easily identified, with its usually paler colour, and darker capitulum, plus its hooded leaves. S. denticulatum can be a little more tricky to resolve, especially if the branches don’t have the ‘cow’s horn’ curvature as described in the books. Tom helpfully noted: “The stem leaves have a defined border reaching right to the base and the cells in the upper part of the leaf are fibrillose extending down well beyond half way. The smooth branch outlines with a lack of a terminal bud suggested it was going to be this species.”
This boggy area kept us engaged for a good time, also finding Cardamine amara (Large Bittercress), for the first time in this tetrad since the recording for the Sussex Plant Atlas was undertaken in the 1970s. Large numbers of the golden, longhorn moth Adela reaumurella were observed too, along with the large cranefly Tipula maxima.
Adela reaumurella
Now time to head back to the car park, we picked up a few more records of common species on Netherfield Road, bringing the tetrad total up to an initially respectable 60, as well as adding a few extra taxa to TQ71I. The day’s walk only included one monad in the target tetrad, and even there it is clear that there are other interesting parts to explore. Furthermore, there is a gypsum mine up in the north-west of the tetrad, so we should anticipate other species turning up as we walk other parts of the square.
Sussex Bryophytes 