About a week ago was my first proper bryophyte outing of the new season. I visited Legsheath Farm in Forest Row with Tom Ottley, the county recorder, and neither of us knew what to expect. The gardens are very mature with lots of stonework and water flowing through the middle, sometimes as a small stream, other times opening out into a series of ponds.
As is usual at the beginning of the season, I felt like I’d forgotten everything, but Tom very patiently described the field characters of species that I know I’ve seen many times before. It was useful, therefore, to revise the common Didymodon species again, additionally aided when I got home by Sharon Pilkington’s useful articles in Field Bryology.[1]
One such species, though common, was new to me: Didymodon rigidulus. Like D. vinealis it grows on calcareous walls, but its leaves are more tapering and with a more distinct nerve. It tends to be a darker green too, and its capsules develop in the autumn, compared with earlier in the year in the case of D. vinealis. The cell shapes, especially in the leaf tips are also different in the two species, and the examination of which was the first bryological application of my new microscope.
Capsule of Didymodon rigidulus with short, slightly-twisted peristomal teeth
Leaf of Didymodon rigidulus, with strong nerve
Small cells in the leaf tip of Didymodon rigidulus
While staring at minute plants on the path, Tom pointed out a liverwort on the soil at its edge. This was the rather lovely Riccia sorocarpa with its distinctive long V-shaped groove.
Riccia sorocarpa
The borders of the various beds in the garden proved to be very rich in bryophytes, one of which was possibly the smallest moss I have yet seen, Ephemerum minutissimum. The plant itself is barely 1mm or so tall, and the capsules are contained by the leaves. There is also a closely related species, which can only be differentiated by looking at the spores, and I’m glad Tom did that, as I had enough trouble getting a look at the plant.
Ephemerum minutissimum
Another abundant resident of the borders was the lettuce-like liverwort Fossombronia wondraczekii. It is the (slightly) smaller of the two common Fossombronia species, and again Tom did his magic to identify it by checking the spores. I’ll get there one day….
Fossombronia wondraczekii
Also on the earth was Pseudephemerum nitidum. Less than 5mm tall, these plants are very fertile and the capsules are surrounded by longer leaves. Compared with the Ephemerum it is a giant.
Pseudephemerum nitidum
The various borders in the garden kept us occupied (and a bit wet and muddy) for some time. We noticed that the Pellia was distinctly reddish and had noticeable male antheridia. Hunting around, Tom eventually found a separate female plant, which had frilly edged tube around the archegonium, making it Pellia neesiana, which is not at all common in the south east, by comparison with the common P. epiphylla, which is monoicous and has a flap-like covering of the archegonium.
The distinctive female plant of Pellia neesiana
Male plants of Pellia neesiana, with a Lunularia cruciata in the background
Finally turning to the stream, it was nice to find Scapania undulata, Dichodontium pellucidum and Fissidens pusillus on the rocks, and especially two good patches of the liverwort Jungermannia pumila which is decidedly uncommon in the south-east, having mostly a western distribution with a few scattered locations in the Weald.
Map of the distribution of Jungermannia pumila
Then a spiky moss on the bank by the stream caught Tom’s eye. Certainly a Pogonatum, but seemed a bit big for P. aloides, so the possibility that it might be the much rarer P. urnigerum had to be considered. After careful examination, Tom noted that it was in fact aloides. Though a bit glaucous, the colour wasn’t quite glaucous enough for urnigerum, and the marginal teeth were not large enough or sharp enough. Furthermore, it had no underground rhizome structure, the apical cells of the lamellae were not broadened, thick-walled or papillose. As Tom said: “It’s right at the top end of the size range for P. aloides and the teeth are quite large too but not really sharp when you look at them under a microscope. The lamella apical cell is quite wrong however so we’ll have to keep looking for that one. It was last seen in East Sussex in the 1950s including a record from the Ashdown Forest area so it’s well worth looking out for. It particularly likes sand and sandstone quarries in Surrey and West Sussex so that’s a habitat you might try if you know of any small pits in the area.”
Pogonatum aloides
In all, we recorded 65 species in the course of the morning, which was a reasonable number and included several nice finds. Many thanks to Mr and Mrs Neal for allowing us to visit.
[1] Pilkington, Sharon. ‘Confusing urban mosses: part I: ground dwellers.’ Field Bryology 104 (2011): 38-43. Web. Available from: <http://rbg-web2.rbge.org.uk/bbs/Activities/field%20bryology/FB104/FB104%20Beginners%20Corner.pdf>. Pilkington, Sharon. ‘Confusing urban mosses part 2: masonry-dwellers.’ Field Bryology 105 (2011): 50-55. Web. Available from: <http://rbg-web2.rbge.org.uk/bbs/Activities/field%20bryology/FB105/FB105%20Beginners%20Corner.pdf>
Diversions in Natural History 