Thursday, 11 January 2018

Hinksey Heights Bryophytes

Botanists enjoying a coffee break in the wood along the valley
Sunday was another winter outing for local botanists, this time on the Hinksey Heights south of Oxford and better attended than the last. Hinksey is in vice county 22 (Berkshire) meaning a day off recording vascular plants for me, but the meeting was focused on bryophytes anyway. The main interest was one of a series of long narrow valleys draining north off the heights, fed by calcareous groundwater emanating from the limestone along the valley sides. There is peat in the upper part of the valley, and it was once an open fen rich in plants such as grass-of-Parnassus but now mostly covered in willow and reed.

The valley is a nature reserve and can be reached from the Hinksey Heights Golf Club via a footpath and board walk leading north-west from the car park (the temptation to botanise which was resisted). The valley opens out at the entrance near its bottom where there are fabulous views of Oxford and its encircling hills to the north and east. The southern slope here supported the only area of Juncus subnodulosus (blunt-flowered rush) fen we came across, but it was rather overgrown.

The stream tumbling over its tufa weirs
This is where we set to bryologising, and as there were a few new-comers to the subject we could share the revelation that is the tiny world of bryophytes, with ample demonstration material provided by the several common species growing on the accumulated fen litter. The only fen moss we found, however, was a scrap of Bryum pseudotriquetrum. The stream within the woodland in the valley bottom had me fantasising of Eucladium and Gymnostomum species, with its spectacular tufa weirs (or barrage tufa) and drifts of petrified leaves and twigs. Tufa is formed where limey waters precipitate calcite (the principle calcium carbonate mineral) onto lower plants and debris, encasing them in stone, and has a specialist bryophyte flora adapted to this highly alkaline environment. The bryophyte flora, however, was rather dull, most surfaces being covered in the pleurocarp Cratnoneuron filicinum, or the thallose liverworts Conocephalum conicum and Pellia endiviifolia. This suite of species followed us up the valley, dominating the weirs, dripping banks of the stream and springs.

The peaty springs higher up were a little richer, but mostly covered in wefts of the common mosses Plagiomnium affine and P. undulatum. Exceptionally, however, and the highlight of the meeting, both species were producing sporophytes, which for P. affine is a very rare occurrence. Most species of Plagiomnium are dioecious (sexes on separate plants) and are shy to produce sporophytes — the only currently known record of P. affine in fruit in Oxfordshire or Berkshire is from nearby Bagley Wood, found by Watson many decades ago.

Fruiting Plagiomnium affine growing with Cratoneuron filicinum in a tufa spring
Like the two Plagiomnium species, most of the mosses and liverworts we recorded were general calcareous woodland plants rather than specialists of wet woodland or fens. We recorded a number of epiphytes such as the increasingly common Orthotrichum pulchellum and O. stramineum, as well as the uncommon and not usually epiphytic Brachythecium glareosum growing on an elder. Altogether we recorded 9 liverwort and 38 moss species, but with a few specimens yet to be examined this is not the final tally. Thanks to everyone for an enjoyable meeting!

Brachythecium glareosum growing on elder (left). The meeting was too early for the pretty capsules of Orthotrichum stramineum (right, April, Blenheim Park) but old dry capsules are distinctively red-brown and flask-shaped.

Wednesday, 3 January 2018

New Year Plant Hunt

Had you been in Peppard on Sunday you might have witnessed Oli Pescott and I striding about the parish, peering into hedges and self confidently looking over garden wall at weeds, for the hunt was on. The New Year Plant Hunt of course, the national scheme run annualy by the BSBI between 30th December and 2nd January, which challenges botanists to find as many wild plants in flower as possible in a continuous three hour period. With Oli for company I managed to do one better than my solo plant hunt which I blogged about last year, and further media coverage was provided with Oli tweeting about our hunt (left). I'd be delighted to hear by any means of other local Hunts, just be sure to submit your records here!

The choice of locality for our Hunt was not the shrewdest as the biggest yields of plants in flower are to be found in areas with a diversity of disturbed habitats, with an abundance of weeds and garden escapes, while Peppard is mostly semi-natural . I thought we'd make it a little bit more fun by seeing how many bryophytes we could find 'flowering' too (i.e. producing sporophytes), and we also kept full lists of both vascular plants and bryophytes! In all we had 20 species in flower, some maybe questionably so — do the cleistogamous flowers of Poa annua (annual meadowgrass) count, and can one ever actually tell whether the tiny-flowered and petal-less Aphanes arvensis (parsley piert) is in flower? In addition to the weeds and garden escapes we had the winter-flowering specialists, with Daphne laureola (spurge laurel) and a male plant of Mercurialis perennis (perennial mercury) on Peppard Common, and some early vernal species such as Ficaria verna (lesser celandine). The total was a few more than my 17 of last year, and better than the bryophytes of which we found only 16 with sporophytes, all commonly producing capsules at this time of year.

Not in flower but the star find of the day was unquestionably the unexpected colony of Saxifraga granulata (meadow saxifrage) in the churchyard of Rotherfield Peppard, seemingly mown with a razor blade. This species had not been seen in the tetrad since the 1960s and previous records (including that of Druce) were unlocalised, so a really good record of this uncommon plant. If you recall, flowering Saxifraga granulata was a highlight of one of the first meetings of the season, lending a nice symmetry to the year. There was further interest among the bryophytes when we found a tiny moss growing on a garden wall — after some head scratching it was suggested that our plants might be the first county record of Leptobarbula berica, but we await confirmation of this.

In total we recorded 173 vascular plant taxa, not a bad haul for December and valuable additional records for Atlas 2020, as well as 51 bryophyte taxa. Oli and I will continue botanising throughout the 'off season', and will next be meeting in Hinksey on the 7th. Please email me if you'd like to join us.

Above: flowering Daphne laureola (spurge laurel) (top) and a male plant of Mercurialis perennis (perennial mercury) (bottom), typical winter flowering plants, found during a New Year Plant Hunt. Right: the delightful sparsely hairy rosette leaves of Saxifraga granulata (meadow saxifrage) growing in All Saint's churchyard in Rotherfield Peppard.

Wednesday, 6 December 2017

Advent Botany at Bix

Large shuttlecocks of Dryopteris affinis growing toward the bottom of a wooded valley on the Nettlebed Estate
Atlas 2020 recording stops for nothing! The first weekend of December saw local botanists taking up their clipboards and setting out into the mist to record vascular plants around Bix (SU78H) in the Chilterns. There wasn't exactly a throng of us, just myself and an extremely keen companion, but we covered a lot of ground, getting together a list of over 220 taxa. Winter can be surprisingly rewarding if you've never looked for plants outside of what is usually considered 'the season' — one just has to be prepared to identify things vegetatively and from dead stuff ('dead-getatively' I call it). Some of the plants usually considered vernal species, such as Erophila verna (common whitlowgrass) or Ficaria verna (lesser celandine) actually start to reappear in autumn and early winter if you know what to look for (the forked hairs on the tiny leaf rosettes of the former are quite lovely!), so you needn't wait until spring!

The Bix area is similar to much of the rest of the Oxfordshire Chilterns, in that woodlands figure prominently and it is under-recorded. One of the things I find interesting in the Chilterns is the mix of geology, with acid clay-with-flints capping the chalk, allowing calcicolous and calcifugous species to grow right next to one another. The woods also often support particularly interesting assemblages of ferns (who cares about the helleborines!), and would be just the right habitat to re-find Oreopteris limbosperma (lemon-scented fern), not seen in Oxon for many decades. As it was, we didn't find it but spent quite a lot of time examining ferns belonging to the Dryopteris affinis aggregate (scaly male ferns), some of which were impressively enormous.

Monday, 27 November 2017

Bryophytes of Godstow Nunnery and Port Meadow, 19th November 2017

Although there are people looking at bryophytes in Oxfordshire and Berkshire, it has been a little while since any records were committed to the British Bryological Society’s database, and we (Oli Pescott, David Morris) have been trying to rectify this with occasional winter excursions. Last weekend we focused on on Godstow Nunnery and surrounds (v.c. 23, Oxfordshire), but with a brief look at Port Meadow to the east of the Thames at the end of the day. (We were almost entirely within SP40Z for the whole day). Surprisingly, there is only one record named in the BBS database as being from Godstow, a record of Syntrichia latifolia from 1951, although it must be the case that some of the older, hectad ‘mastercard’-type records from SP40 in the database would have been made there. The length of old walls at Godstow makes it unlikely that Oxford bryologists of yesteryear would have failed to visit it. Godstow is also a prime spot for list-makers, being one of the few established populations of Aristolochia clematitis (Birthwort) in Britain, making it doubly odd that no-one has made a clearly localised list of bryophytes there that has made it into the BBS database.

Godstow Abbey ruins
© Copyright Chris Gunns and licensed for reuse under this Creative Commons Licence.
But enough of what hasn’t been done, and on to the plants that we saw. Despite the lovely bright day, we conspired to spend most of the morning in the shade, examining the north-facing walls of the ruined abbey. The old damp stonework hosted some lovely populations of the liverwort Porella platyphylla (which we failed to photograph – apologies dear reader!), as well as other denizens of such places like Anomodon viticulosus and Neckera complanata. Of course, smaller acrocarps (the ‘cushion’-type mosses) were also in abundance, with, in random order, Bryum radiculosum, Didymodon vinealis, Syntrichia montana, Syntrichia ruralis, D. insulanus, D. luridus, Pseudocrossidium revolutum, and Orthotrichum anomalum all putting in appearances. There was plenty of Ceratodon purpureus too, and, in fact, the D. insulanus was only confirmed later on at home after ploughing through several collections of spindly C. purpureus (an impressively variable moss, but this plasticity more often draws sighs of frustration rather than admiration from field bryologists). After adding a range of other wall-dwelling bryophytes to our list, including some additional pleurocarps, we examined an area of stone embankment retaining the Thames: Cinclodotus fontinaloides, Lunularia cruciata, Crateneuron filicinum, and Platyhypnidium riparioides were added to the list in quick succession.

Post-lunch, we briefly examined some tarmac on the wrong side of Godstow Lock, adding a number of what the eminent bryologist Des Callaghan has been known to refer to as “townland treasures” (as opposed to the more frequently heard “grots”), before being asked to sling our hook by the lock keeper, and this wasn’t an invitation to sample a different hobby whilst water-side. The most interesting addition from the tarmac was Didymodon nicholsonii. Further south in a strip of mixed deciduous woodland (with an impressively large Field Maple), we added a small selection of epiphytes, including Syntrichia papillosa on Oak, S. latifolia (the one species previously localised from the area) on felled Salix, and a few more liverworts such as Metzgeria consanguinea, M. furcata, and Frullania dilatata. Investigations of Zygodon tufts at home later on revealed Z. conoideus and Z. viridissimus. These are species that are, by and large, quickly distinguished by dislodging gemmae from the leaves onto a slide; if you have a stereomicroscope but no compound microscope, the gemmae can even be distinguished at x40 on a white background (although one could miss rarer species in this fashion).

Syntrichia papillosa
By Des_Callaghan (Own work) [CC BY-SA 4.0]
Given that we were in the area, we decided to investigate a couple of spots on Port Meadow before heading home. This turned up the tuberous Bryum, B. klinggraeffii, from fine sand and gravel on a bend of the Thames. Sometimes called the Raspberry Bryum, the tubers on this species’ rhizoids are dark red and have large, protuberant cells; unlike some plants, the Raspberry Bryum is well-named, and the eye-of-faith needn’t enter into it. Although frequently recorded from Berkshire over the past 30 or so years, this is a species that has only very rarely been found in Oxfordshire, although how much of this is due to a lack of habitat, and how much is due to under-recording, it is hard to say. Further south, in the area of low-lying land in Port Meadow that regularly floods in winter, the mud of the draw-down zone yielded more B. klinggraeffii, and, on returning home, Aphanorrhegma (Physcomitriella) patens was discovered on the edge of a clump of the former species. Again, this is probably somewhat under-recorded, but according to BBS data at least, has not been recorded for the vice-county since the 1980s. (Although it was seen nearby on a track by Wytham Wood in v.c. 22 by Chris Preston in 2007). The draw-down zone of Port Meadow might repay further investigation, as, with its use by geese and other birds, it could be the sort of place that one could turn up Ephemerum cohaerens, a nationally rare moss that occurs in similar habitats, and may be moved around by migrating bird life.

The full list of species seen across all the squares is given below. We hope to see you at a future excursion! The next planned date is the 10th December.

Barbula convoluta var. sardoa
Zygodon viridissimus var. viridissimus
Platyhypnidium riparioides
Lunularia cruciata
Barbula unguiculata
Zygodon conoideus var. conoideus
Rhynchostegium murale
Metzgeria consanguinea
Didymodon nicholsonii
Orthotrichum affine
Rhynchostegium confertum
Metzgeria furcata
Didymodon vinealis
Orthotrichum anomalum
Rhynchostegiella tenella
Porella platyphylla
Didymodon insulanus
Orthotrichum cupulatum
Oxyrrhynchium hians
Frullania dilatata
Didymodon luridus
Orthotrichum diaphanum
Kindbergia praelonga
Didymodon sinuosus
Ulota crispa s.l.
Brachythecium rutabulum
Aphanorrhegma patens
Tortula muralis
Bryum capillare
Homalothecium sericeum
Schistidium apocarpum s.l.
Phascum cuspidatum
Bryum argenteum
Calliergonella cuspidata
Grimmia pulvinata
Syntrichia ruralis var. ruralis
Bryum radiculosum
Hypnum cupressiforme var. cupressiforme
Fissidens taxifolius
Syntrichia montana
Bryum klinggraeffii
Cryphaea heteromalla
Ceratodon purpureus
Syntrichia papillosa
Cratoneuron filicinum
Neckera complanata
Pseudocrossidium hornschuchianum
Syntrichia latifolia
Amblystegium serpens
Thamnobryum alopecurum
Pseudocrossidium revolutum
Cinclidotus fontinaloides
Leskea polycarpa
Anomodon viticulosus