DHBlog016 · A bryological dreamland? An article by Robert Sharp
A small group of bryologists have been surveying the Chines of Bournemouth this winter, for want of anything better to do. Much to our surprise, the results have been very interesting, especially the Upper Gardens in Bournemouth. But it was perhaps with relatively low expectations that Lyn Petersen, Mark Dale and myself entered Alum Chime in late November 2022. Little did we know...
I woke up this morning with a strong sense of having dreamt yesterday. Did it really happen or were we transported in our sleep to the Scilly Isles? Here is how I remember the dream.
Is that Dicranella heteromalla growing on a vertical stone wall? Apparently it is, and nothing that odd about that, perhaps, but isn't that Neckera smithii growing on the same wall? Yes, it is! What is it doing here and why is it on a wall? How strange.
We admire the tiny green lawns of Cephaloziella dotted here and there. A bridge; surely familiar ground for cushions of Didymodons and Syntricia? Nope, only Feather-mosses growing here. Isn't that Scleropodium cespitans on the tarmac, and again growing on the metal railings? Yes, despite being uncommon in Dorset and no mention of the railings. And is that Plagiomnium rostratum on the tarmac with it? It is! But where, then, is the water, the rushing streams, the waterfalls? Under the bridge we are standing on, but then somewhere further underground, where those manhole covers give it away? Not really the setting you would expect for these two.
The stonework on the bridge looks normal and thankfully it is, but over the wall and on to the steep banks and surely that isn't, is it? It is! Its Thamnobryum alopecurum growing on a tree beside the bridge. But this isn’t the right soil for that, is it? Well, there is Neckera complanata growing on the same tree. Both common on the chalk, so it all seems unlikely, but isn’t that Thamnobryum growing all over the wall beneath the bridgehead? Not quite; there's also a fair bit of Neckera on the wall with it. Do they do that, grow on walls, I mean? Apparently they do, but perhaps not very often.
An old tree stump brings relief in the form of the pleasantly scented liverwort Lophocolea heterophylla and down at the bottom of the bank, on a rotting log we find more of the Cephaloziella from earlier. Wait, surely those leaves have three fingers, not two? It can't be Kurzia, can it? No, but look in the field guide, there on the opposite page. Isn't that it? And there is even a dot on the map that must be us. Its Telaranea murphyae, isn't it. Bournemouth and Poole get a mention in the guide, as well as the Scilly Isles. Wow, what are the chances of finding that? Well, pretty high it seems, because its everywhere down here. In fact there are fallen trees literally covered in the stuff. And that Cepheloziella earlier? Yes, its actually Telaranea as well.
The middle of the day passed without any further surprises and in fact things returned to normal when we reached the seafront. Where there were once unusual bryophytes (Mesoptychia turbinata and Campylopus fragilis) there are now beach huts. Hang on, we've lost Mark. Oh, there he is and he's got some more mosses from under the pines opposite. What is that? It's definitely the leafy liverwort Lophocolea, but it hasn't got any bifid leaves at all. Could it be the rare Lophocolea semiteres? Well, why not! Lets make a day of it. Guess where it is more often found? The Scilly Isles, together with its associate, Teleranea murphyae!!
Perhaps it wasn't a dream after all? I went back later to check. The mosses were all still there, and in fact another downland moss had joined them: Anomodon viticulosus. So it can’t have been a dream, can it?
Notes on some of the species recorded:
Dicranella heteromalla is a small dark green moss that often grows in little lawns on the steep sides of woodland banks, especially where there is a little clay. We found quite a lot of it scattered around the Chines, but it is unusual to find it growing on a wall, especially where there is no discernible layer of soil between it and the stonework.
Neckera smithii, which was previously known as Leptodon smithii and has the evocative English name of Prince of Wales Feather-moss, is a distinctive epiphyte that is most often seen growing on maple or sycamore trees in deepest rural Dorset. When dry it looks quite drab but on wetting with a handy spray bottle (carried by most bryologists) the dried fronds gracefully unfurl to explain where it got its name from. (Update: that was my interpretation, but apparently the name comes from the tightly curled dry fronds!) Finding it in Alum Chine was a big surprise, especially on a wall. There weren’t many tree-based epiphytes within reach so I would expect it is growing somewhere high up on a few trees nearby.
Scleropodium cespitans. The only time I have seen this moss is in Somerset, smothering the bole of an old tree. Our group leader expressed disbelief when I said I had not seen it before. When I got home I checked the Dorset Atlas and it is unusually scarce in Dorset. Of course, technically Alum Chine is in vc11 and not vc9, but its right on the border. It is also unusual being found on tarmac, let alone metal railings. It got something right with growing on the bridge, but not with the water that isn’t flowing under it.
Plagiomnium rostratum is a moss that looks a bit like a vascular plant with large round leaves spaced neatly along it stems. We found a lot of it along the banks of the Bourne Stream in Upper Gardens, but here there is no stream and it is growing through the Scleropodium on the surface of the bridge.
Thamnobryum alopecurum is typically found growing on the floor of woods in base-rich soils. The branches are elevated on little tree-like stems and under the microscope it is one of the few Feather-mosses (Pleurocarps) that doesn’t have long, thin cells. It often grows up the base of trees, but in Alum Chine it wasn’t growing on the soil at all, which is hardly surprising. I suspect the main colony was on the damp and base-rich vertical wall that supports the bridge head and from there it has colonised a few trees close by. I wonder how it ever got here?
Neckera complanata is an epiphyte but shares a similar range to the Thamnobryum. Presumably they arrived together. It was even more surprising to see it growing on the damp stonework beneath the bridgehead.
Telaranea murphyae is the central actor in our dream. It was first discovered in 1950’s on the isles of Scilly and for a long time there were no other plants known in the world. More recently, following several studies, Jean Paton concluded that it was in fact a male clone of another species, Tricholepidozia tetradactyla and that some confusion surrounding a sample from New Zealand had apparently obscured this. But why is it growing in Alum Chine, as well as neighbouring Branksome? Did it, perhaps, get here from the Scillies as part of the tropical gardens that are at the seaward end of the chine? And why hasn’t it spread? Perhaps the microclimate of the chines creates the climatic conditions necessary and missing in the wider Poole basin. Certainly as a male clone, the spread of the plant will be limited to asexual reproduction, but judging from the extent of growth within the chine, it is clearly good at that!
We later found more of this liverwort growing in Middle Chine, east of Alum Chine, and we did not find any growing in the tropical gardens. It appears to prefer sheltered nooks and hollows that are probably well protected from the winds nearer the chine mouths. If you were to look in the gardens between Alum and Middle chine it would not be surprising to find a few more communities.
Lophocolea semiteres is a leafy liverwort and a neophyte that has been spreading across Southern England in recent years. It is not too difficult to identify if it is fertile, the antheridia (male flowers) are all on their own and are very distinctive and immediately apparent under the microscope. I hadn’t been aware of the species until earlier this year and had wondered if we might see some on our surveys of the chines. It has previously been recorded on nearby Southbourne Cliffs. We subsequently found a lot of it growing around the wooded edges of the Tropical Gardens, but so far we have not seen it anywhere else. It could have arrived from the Scillies with the Tricholepidozia and remained close by while the latter retreated deeper into the chines looking for shelter.
