I’ve not done much recording over the last few weeks, so yesterday continued working on my home hectad, focussing on the area to the east of Hartfield village centre and over the parish boundary to Withyham. My plan was to do a nice circular walk through Buckhurst Park, stop off at Withyham churchyard and then back to Hartfield, but I barely got into Withyham.

Hitherto 14 species have been recorded in the tetrad, almost all from 1968, and two intriguing ones from 1980, Frullania tamarisci and Zygodon rupestris, recorded by Francis Rose, Rod Stern and Howard Matcham, and I’d love to know where they were.

Striding across the rather unpromising arable field by Hartfield church, I found the first plant that confused me. Tom helpfully pointed out that it was Dicranella staphylina, the only common species in the genus that I’ve not really looked at microscopically before. At least I have some useful pictures of it now.

Dicranella staphylina

The second acrocarp for which I needed some help from Tom was one which had gained a foothold on a tiny bit of sandy soil on some timber by the edge of the stream that forms the parish boundary. It turned out to be Dichodontium pellucidum, with its dentate leaf apex.

Dichodontium pellucidum

Leaf apex of Dichodontium pellucidum

At the same spot I noticed something growing on the bed of the shallow stream, and managed to grab a sample without falling in. Clearly a curious-looking alga, when I got it home all its magnificence could be seen, and Howard Matcham helped identify it as Batrachospermum gelatinosum, the third Sussex record.

Batrachospermum gelatinosum

I always rather like crossing watercourses that are parish boundaries, knowing that they have probably been recognised since the middle ages. The brick bridge crossing was home to several species one would expect, such as Tortula muralis and Homalothecium sericeum, as well as a couple of Didymodons (vinealis and insulanus), a genus which I’m now  feeling  more confident with.

The wood on the Withyham side of the stream is called Bog Shaw and should reward further exploration. Following a flush down towards the water led me to a nice patch of Scapania undulata, with some Chiloscyphus polyanthos, overshadowed by Oenanthe crocata (Hemlock Water-dropwort) and Lycopus europaeus (Gypsywort).

The Scapania site

By now running out of time I ventured down another small shallow runnel and found a pleurocarp on stone in the water. This had me puzzled, and I was tending towards Hygroamblystegium, but Tom put me right again, explaining that it is a small form of Cratoneuron filicinum.

Cratoneuron filicinum leaf

Alar cells of Cratoneuron filicinum

“It’s a small form of it and lacks many of the usual features so you may find it hard to see any paraphyllia for instance and it may not be obviously pinnate either.  In the second photo you can see part of the wings that join the leaf to the stem.  These are sort of below the leaf and form triangles and you will find the cells are thin-walled there.  These alar patches are in a rather different place to Brachythecium for example where they tend to include the widest part of the leaf base.  Most of the so-called hook-mosses have this arrangement.  Anyway, Cratoneuron also has teeth around the widest part of the leaf as one of your photos shows and that seems a particularly constant and therefore useful feature.”

Toothed lower margin of Cratoneuron filicinum

Even though Tom is in Wales, I’m still learning from him. With his help that has taken the tetrad count up to 44 I think. My next visit will finally get me to the churchyard and the footpaths of Buckhurst Park. There must be lots more to find.