Nature Notes from Argyll
(and occasionally other places)
Sat 5 May 2007 Glen Lonan
First Wheatear seen, though they've have been around for at least a month. First midges too :-(
The valley of the River Lonan is a mix of grassland and woodland, but at no great height up its slopes the moorland starts. These are two of its commonest plants, still at the flowering stage though more familiar when in fruit. Common Bog-cotton and Common Sedge.
We had the Oak Fern the other day but I couldn't resist this striking patch of bright green in the woody shade. There were about a hundred stems of the fern all crowded together like this, and no others anywhere round about. In Skye it was more a plant of mountain rock crevices and boulder scree, but it looks its best in woods.
The moss Rhizomnium punctatum also formed a bright patch in a dark wood. It was low down on the muddy bank of a trickling stream. The upper leaves are translucent and surround the dark antheridia.
Some patches of woodland or scrub on the slopes had quite a rich flora, including Dog's Mercury, Woodruff and Sanicle.
This stonefly (Isoperla grammatica) was crawling about on grass stems and moss not far from the river. It's called the Yellow Sally though it looks distinctly green to me. The body is quite a bit shorter than the wings, but has two long tail-streamers which you can perhaps make out diverging from beneath the wing-ends. The Wolf Spider (Pardosa sp) was on a rock at the river's edge.
Saw several Green-veined White butterflies and a Brown Silver-line moth.
The river level is very low after the long spell of dry weather. This willow has yet to put out any leaves but its catkins make a bright display.
DRY STONE WALL SURVEY
This year I'm taking part in a national survey of the flora of dry stone walls. I drifted into it but am finding it totally absorbing. Dry stone walls are a very difficult habitat for plants to colonise and have nothing like the rich vegetation of mortared walls. In this part of the world the dry stone walls are made of acidic rock whereas mortared walls can support lime-loving plants. Mortared walls also have much narrower crevices in which a plant's roots can secure themselves. Dry stone walls are just rocks and air. Like a shingle beach greatly enlarged and turned on its side.
The initial colonists of dry stone walls are usually lichens and mosses. As the older parts of these break down they provide a kind of "soil" in which vascular plants can sometimes get a foothold, but generally speaking vascular plants are few and far between along a dry stone wall, and the variety of species is very limited.
My first task is to get to know the regularly occurring wall mosses. I've not made a very promising start at this, as I find mosses the most difficult of all organisms, except perhaps spiders, and the moss books I have are not written in any spirit of goodwill towards the novice. By far the best resource I've found is the British Bryological Society online field guide, although it is only of use once you know the name of the species you want to look up, and it does not yet cover all species. But the descriptions combine the essential microscopic features with notes (and pictures) describing the moss's general appearance and the points that distinguish it from similar species.
Today I found 3 suitable walls - in the coming weeks I'll look for more. Wall A had the lichens Sphaerophorus globosus and Rhizocarpon geographicum, the latter being the only small crustose lichen I can recognise and possibly the only one I'll include in the survey, but I'll include all non-crustose lichens, whether I can recognise them or have to look them up. The only vascular plants on Wall A were a small group of Wood Sorrel growing on the top among moss at the end of the wall which was under trees.
Wall B also had one end under trees, and here the moss covering was so thick that you could not see any stone. At this point I started to take photos of the principal mosses, and bring home small samples to examine.
Note: all the mosses below were in very dry condition when their photos were taken, and any descriptions that I've given also apply to dry material. Many mosses look very different when they are wet.
This is the only one that I've been able to positively identify so far, Thuidium tamariscinum, looking like a miniature Cypress tree.
I can get nowhere with either of these, though the first is very distinctive, and as soon as I happen upon a picture of it I'll know it. Like the previous species, it hung profusely over the wall sides. (20th May: it is Rhytidiadelphus loreus). The second was less rampant but formed small cushions among the other mosses. Its leaves have a dark V at the base made up of thickened cells along the leaves' basal margins. The leaves spread at 45° from the base and then curve up slightly. They are c 2 mm long, translucent, and minutely toothed, but this is very hard to see. Their midrib ends, or becomes very faint, about 2/3 of the way up, and they end in a long hair-like point the same colour as the rest of the leaf. Stem glabrous, green, becoming dark when older. Shoots well-branched, at least bi-pinnately, but not at all regularly.
This one came out close to Dicranum scoparium but fails the tooth test as I could see no teeth on the leaves anywhere. They are c 7 mm long, 1 mm wide just above the base, with pale midribs which are quite broad but not as broad as half the leaf until near the tip. The stem has a white matted tomentum. The RH moss is an erect one growing out of the prostrate mosses on the top of the wall, just a small patch. It is clearly a Polytrichum species, but I'll have to wait for fruit befofe I can tell which.
At this shaded end of the wall, Wood Sorrel was quite frequent among the moss. The rest of the wall, which was not shaded, had the occasional grassy patch on top looking at first as if someone had placed a turf there. On examination there was no soil but several cms of rotted moss, which supported the grass (which included Sweet Vernal Grass and possibly others) and other vascular plants such as Tormentil, Hairy Woodrush and Dog Violet. In one place Heath Bedstraw was growing among moss without grass, and there were also a couple of small Rowan seedlings on top of the wall.
Wall C (above left) had a Rowan some 6-8' tall growing out it! The greatest concentration of vascular plants was around the base of this tree, with one Foxglove rosette, a patch of grass (to be identified when it flowers), another Rowan seedling and some Common Polypody. This latter was frequent all over the wall, and was the only vascular plant to be found away from the vicinity of the Rowan. It did not occur on Walls A and B. The RH pic shows our old friend Frullania tamarisci, which was all round the base of the Rowan and had spread to the stonework of the wall. You can see the dark red patch on the Rowan pic. It will be interesting to see if I find this species elsewhere on walls, or if the only way it can get onto a dry stone wall is if a tree grows out of the wall first.
Just to the left of the Frullania (which you can see a bit of in the top right) is this twisty little moss which again keys out to somewhere near Dicranum scoparium, though it is very different from the one that did so earlier, as that had conifer-green leaves and a hanging habit, while this one is yellow-green and forms a turf of squat short stems. For once it was a moss with fruit capsules, but they were no help. They were equally unhelpful on the moss in the RH pic, which has the leaves crowded and appressed at the top of the stems looking, when dry at any rate, like bunches of red bananas, so I'm going to call it Red Banana Moss until I find out its real name (and probably for a long time afterwards). I believe the effect is called a comal tuft. Lower down the stems there are just a few "stem leaves". The calyptra is fibrous which at first gave me great hope but the trail went cold. The capsule opening has at least 32 teeth. The leaves are perhaps 4-5 mm long + 1-1.5 mm for the hair-tip, and the topmost leaves are green as the picture shows. The hair-tips are deciduous; the lower leaves tend to lack them. When bent back, the hidden top side of the leaf shows a midrib and a large sheathing base like that on Polytrichum. (15 May: have finally worked out that this moss is Polytrichum piliferum. I was put off Polytrichum by the fact that our capsule did not have an epiphragm, but perhaps these fall off over time? Also the book makes no mention of the reddish colour but says the plants are "glaucous"!)
Well after that I'm not going back to writing "Unknown Wall
Moss" in the alt tags, so this one can be called Smoky Wall Moss. It was
very common on Wall C forming big fluffy cushions on the tops and sides.
It also occurred on Wall A. It is instantly recognisable, even from a
distance. Under the microscope, the leaves have long white toothed
hair-tips which, a bit lower down, become white margins to the top of the leaf.
(15 May: this is Racomitrium lanuginosum)
All photos and other content copyright © Carl Farmer