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.

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.

Liverworts	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
Mosses	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

Loddon pondweed... IN THE THAMES!

I do not use capital letters lightly: the rediscovery of Potamogeton nodosus, the so-called Loddon pondweed, in the River Thames is really very big botanical news indeed! Otherwise known only from the River Loddon, the Bristol Avon and the Dorset Stour, this very rare pondweed was thought to have gone extinct in the Thames in the 1950s and there have been no Oxfordshire records for over 75 years. It was found by Frank Hunt back in August, near Marsh Lock, just south of Henley (SU774815), growing in a part of the river sheltered from boat traffic by a footbridge. Marsh Lock is less than 1km downstream from where it was seen by J.E. Lousley in 1941 and about 5km below where the Loddon joins the Thames. Frank also tells me that there is a patch in the the Berkshire part of the river too.

This is such a distinctive species that the referee for pondweeds, Dr Chris Preston, was quite happy to verify the record from the photograph shown right (and attributable to Frank).

Stadhampton Square Bash

Puccinellia distans along the A329

Last Sunday was another square bash, when we moved on to Stadhampton (SU69E) from our previous visit to Little Milton (SP60A). Sorry it has taken me so long to write the meeting up! Let's see if I can make it a short one for a change.

As last time we started off with coffee and cake — may this become an established tradition, especially as the weather begins to turn cooler! Many thanks to Fay Banks and her granddaughter for baking delicious brownies for the four of us. After this pleasant diversion from the task of the day we headed out recording. When botanising any village a priority will always be the churchyard and this is where we went first. It was the usual disappointment, ruthlessly mown, but sported Galium verum (lady's bedstraw), Pimpinella saxifraga (burnet saxifrage) and Plantago media (hoary plantain),  a typical assemblage of hangers-on in over-managed churchyards. We did find Epilobium x limosum in a weedy patch, the hybrid between the broad-leaved and hoary willowherbs — no surprises to learn on getting home that this hasn't been much recorded in the county.

Two buckler ferns: the broad Dryopteris dilatata (left) and the narrow D. carthusiana (right). The latter used to be called D. spinulosa on account of the long drawn-out points to the pinnule lobes, and it lacks the distinctive black-marked rachis scales and convex shape of the pinnules seen in D. dilatata.

Stadhampton pond infested with Myriophyllum auqaticum

Square bashing is mostly about gathering as many records as possible from a square, and in settled places this usually consists of alien species, but one seldom fails to find something of interest. Along the A329, for instance, we had a couple of decent and probably under-recorded grasses: Puccinellia distans (reflexed saltmarsh grass), a colonist of salted roads whose natural habitat as the name indicates is on the coast; and Polypogon viridis (water bent) a grass that been expanding in range very rapidly in urban places over the last decade or two but as yet has few Oxon records. Other aliens were in plentiful supply, particularly the invasive Myriophyllum aquaticum (Parrot's feather) which had taken over the pond on the village green.

Returning to natives, the limestone walls of the village had the usual Polypodium (polypody fern), unidentifiable at this time of year. However, a little later on once we'd got out in more semi-natural habitat we came upon a nice big stand of well-behaved Polypodium growing on a concrete bridge over a stream and which was clearly P. interjectum. As I've commented in previous posts this would seem to be our commonest Polypodium species. A little further on we came upon some lovely alder woodlands that had developed over a series of medieval fish ponds. Often getting good records is a matter of knowing what to look for in particular places, and here we managed to find the wet woodland fern Dryopteris carthusiana (narrow-leaved buckler fern), a pretty scarce plant in Oxon. Interestingly, the few recent records come from Chiltern beechwoods, an atypical habitat.

The woodlands served us well and were a nice contrast for a square that mostly comprised artificial habitats. The total for the square is now 250 taxa, a considerable improvement from the 9 it had stood at. Many thanks to those that attended.

Aston Rowant Roses

Geoff Jones examining Rosa rubiginosa on Beacon Hill against the backdrop of the Oxfordshire plain

Late summer and early autumn is the best time to identify wild roses if one is game for the challenge. While it is a challenge, there is so much we don't know about the status and distribution of Rosa taxa in the county that their study really pays off I have found (though I am by no means an expert). I believe Geoff Jones, new to roses and a volunteer recorder at Aston Rowant National Nature Reserve, whom I met there on Saturday to spend a few hours rhodologising, has come to be of the same opinion. I will always be delighted to hear from botanists such as Geoff who are intrigued by these beautiful plants and would like to record them thoroughly. I hope the following account of our short visit will give you an idea of what could be out there to be found in your patch.

Aston Rowant NNR is of course well-known for its chalk grassland and woodlands, but it is also a very scrubby place and this is where to look for roses. Some of the scrub is very old and these are the best places to hunt for unusual roses. We started on Beacon Hill where Geoff had already puzzled over a few potentially interesting roses. In scrubby bits of downland we found several grotty bushes of two sweet-briars, Rosa micrantha (small-flowered) and R. rubiginosa (sweet-briar or Eglantine). The UK has three native species of sweet-briar — the third, R. agrestis (small-leaved), was only rediscovered in the county last year at nearby Pyrton Hill.

Little Milton Square Bash

Alien grasses sown for game, Ecinochloa crus-gali, Panicum milliaceum and Zea mays

It is some time since I posted on here, which is a shame, but the season (work) had the better of me for a while. However, this weekend I managed to get out again with local botanists and gather some much needed records. For those of you who might have missed my botanical waffle, here's an account of what we got up to.

Now that SP42 is looking better recorded I thought I'd turn my attention to another under-recorded area, roughly the Oxfordshire part of the Thame catchment, from a few miles south of Oxford east to Thame and pretty much all the way to the foot of the Chilterns. As it is mostly arable land with very few nature reserves or similar sites one can appreciate why it might not appeal, but it still needs doing. A few botanists have been working on it, but it is a large area and there isn't much time before the end of the recording period for Atlas 2020. Wanting to contribute to this effort, therefore, six of us met at Little Milton where we were very kindly treated to tea and freshly baked cake by resident botanist Liz Powell. The tetrad (SP60A) has had some recording already so I had hoped to make it toward Stadhampton (SU69E) in order to cover new ground. Hardly surprisingly we didn't get that far, but we added a lot to the tetrad total for Little Milton, getting it up to 288 taxa. Of course there were a host of the usual garden escapes but the total also includes some more unusual and interesting plants.

The first species of interest were along the A329, where we had Torilis nodosa (knotted hedge parsley), a characteristic plant of dry, well-mown verges, and Lactuca virosa (great lettuce). The latter is a colonist of roads that is still relatively uncommon in Oxfordshire but that is everywhere if one botanises further south or east. Botanising late in the summer we were also able to identify damsons (Prunus domestica subsp. institia) rather than having to leave bushes unsatisfactorily as wild plum (P. domestica).

Middle Barton

Another successful recording meeting in SP42 last Sunday (apologies for the delayed write-up). After all those records from TVERC the hectad now looks relatively well recorded, but there were still no recent records from Middle Barton Fen SSSI (SP42N), so recording this site was the goal. With just three attendants we were able to cover ground quickly, getting round the site in good time so as to be able to also fit in a thorough bashing of SP42M.

Initially it didn't look positive that'd we get access to the SSSI so we wandered across nearby improved pasture. We made some surprising finds here on the slope above the fen, the first of which was Filipendula vulgaris (dropwort). There were also several rosettes of Cirsium acaule (dwarf thistle) and clumps of Ononis spinosa (spiny rest-harrow). The best find was Alchemilla filicaulis (hairy lady's-mantle), known at only four sites in the county and not seen at Middle Barton since 1987. After this splendid discovery access was confirmed to the SSSI!

The SSSI along a shallow valley of a small stream is in unfavourable condition, with much of it rank and overgrown with Filipendula ulmaria (meadowsweet). There was a little Dactylorhiza maculata (heath spotted orchid) in this vegetation, but the grazed neutral grassland on the valley slope was in good condition with plenty of nice plants, including Briza media (quaking grass), Dactylorhiza fuchsii (common spotted-orchid), Galium verum (lady's bedstraw), Potentilla erecta (tormentil), Poterium sanguisorba (salad burnet) and Succisa pratensis (devil's-bit scabious).

Another field within the SSSI still supported the distinctive fen meadow community dominated by Juncus subnodulosus (blunt-flowered rush) and Carex acutiformis (lesser pond sedge). Here the vivid green of rush and sedge foliage was splashed with the brighter colours of F. ulmaria and Silene flos-cuculi (ragged robin), as well as a mass of the pale straw-coloured inflorescences of J. subnodulosus. There was also an abundance of the scarce Valeriana dioica (marsh valerian), the un-valerian-like basal leaves forming an understorey to the rushes.

As we'd finished looking round the fen by lunchtime we next headed to SP42M which had only 80-odd post-2000 records. This tetrad supported a decent diversity of habitats, with wooded lanes, road verges, hedges, a churchyard, grassland and small streams with fenny areas, and we found a respectable 193 taxa. This bumped the tetrad comfortably over the 200 mark, including a few near-threatened species such as Knautia arvensis and relatively scarce ones such as Ranunculus fluitans (stream water-crowfoot).

For the next meeting on the 9^th July we'll be back in SP42, returning to SP42Z. We were there way back in May and this time we'll be surveying Bestmoor SSSI which holds a large population of the nationally scarce Oenanthe silaifolia (narrow-leaved water-dropwort). Supposedly there are tens of thousands of plants and as well as count these I've been asked to survey the vegetation — I'll therefore be needing lots of help should you be able to spare a Sunday!

A big thanks to Thames Valley Environmental Records Centre

... and of course to all the botanists who submitted records to TVERC! All 340,000+ of TVERC's plant records for vice county 23 (Oxfordshire) now reside in the BSBI's Distribution Database (DDB), and my word what a difference it makes! The records go as far back as 1794 but most local recorders will want to know how it affects coverage for Atlas 2020 — see below!

The arrival of so many records is a result of a data sharing agreement struck between the records centre and BSBI. In return TVERC receive regular updates of records that come through me as county recorder. BSBI members often wield a more critical eye, recording esoteric taxa such as hybrids, taxonomically critical groups of plants and unusual garden escapees, so perhaps this will improve the coverage of their database. TVERC also get an extra pair of eyes validating their plant records, and this is what I will be doing over the winter, checking all of their hundreds of thousands of records! That's a lot of work but worth it for the great improvement it makes to the BSBI's data holding for Oxfordshire.

Out Wood SSSI

A botanical meeting was held on Sunday at Out Wood Site of Special Scientific Interest (SSSI), near Kiddington (SP42A). This was a return to square bashing for Atlas 2020 after a previous jolly to Otmoor. The square had a small number of recent records and the plan was to boost this by taking in a mix of habitats including the SSSI and surrounding farmland. The SSSI citation sounded quite tantalising, so I was hoping for some goodies, perhaps even Ornithogalum pyrenaicum (spiked star-of-Bethlehem). The site is in unfavourable status so I wasn't feeling too optimistic

The participants (seven botanists plus a dog) met at Grimsdyke Farm, named after an ancient fortification that runs through part of Out Wood. Along the walk to the wood was a narrow spit of woodland emanating from Out Wood but not part of the SSSI. Here we recorded most of the woodland plants that we would also find in the SSSI, including Allium ursinum (ramsons), Conopodium majus (pignut) and Elymus caninus (bearded couch), and at least one that we didn't, Ranunculus auricomus (goldilocks buttercup). Arriving at the SSSI it was evident that the grassy rides advertised in the SSSI citation were gone: most of the flora was of shade-tolerant clonal species such as Mercurialis perennis (dog's mercury). I'm sure the place had looked lovely earlier in the year given the abundance of fruiting Hyacinthoides non-scripta (bluebell).

We spent a while working the wood, turning up a suite of common ancient woodland plants, including quite a lot of Epipactis helleborine (broad-leaved helleborine) and a few over-done spikes of Orchis mascula (early purple orchid). For the most part the wood was monotonous, and some areas had been planted with Fagus sylvatica (beech) and other forestry trees. However, parts had been deer-fenced to allow coppicing and tree planting and we hoped the increased light, disturbance and exclusion of deer might turn up some plants of interest. We managed to get into the coppice coop containing Grims Ditch but it was a thicket of Rubus fruticosus (bramble). Here we recorded Lithospermum officinale (common gromwell) and the hybrid between Juncus effusus (soft rush) and J. inflexus (hard rush) known as J. x diffusus. We seem to have been the first people to record the latter from Oxon since Druce in the 1890s.

At lunchtime half of the party left and the remainder abandoned Out Wood for a better mix of habitats. Some grassy areas in woods to the east were quite productive with e.g. Hypericum maculatum (imperforate St John's Wort) and Mentha arvensis (corn mint) and what I think might have been Euphrasia arctica (arctic eyebright). The latter is more of a northern/western species with no recent Oxon records. On the route back to the cars was a rather sad hedgerow with a few limestone grassland species hanging on against the assault from intensive cereal farming: here we recorded such delights as Helianthemum nummularium (common rock-rose) and Knautia arvensis (field scabious) and a large quantity of Carex leersii (leers' sedge, syn. C. divulsa subsp. leersii). A bank near the car had a better-preserved limestone grassland flora, and we added Linum catharticum (fair flax) and Ononis repens (restharrow). We also managed to find some good arable weeds with both Kickxia elatine and K. supuria (sharp- and round-leaved fluellens) and Chaenorhinum minus (lesser snapdragon).

Thus while Out Wood SSSI was somewhat undistinguished we gathered a good number of records, 220 taxa in all making the tetrad total up to 231. To be sure there will be more to be found but that's a good start and improves the county's Atlas coverage. Thanks to all who took part!

Otmoor

The hybrid Viola x ritschliana between the nationally rare and critically endangered fen violet and the locally rare heath dog violet.

Otmoor Site of Special Scientific Interest was the venue for my latest recording meeting, held on bank holiday Monday. The area has been thoroughly botanised over the last few years so the purpose of the meeting was largely to have fun and see one of the finest wet grassland sites in the country, but I had hoped to add a few records. We were joined by members of the Reading and District Natural History Society. I didn't count but with Oxfordshire Flora Group regulars we made up an exceptionally large group (whom I kept waiting for twenty minutes when I mis-remembered the start time!).

I know the Moor well but this was only the second occasion I'd had to access the area around the MoD firing range. There are many wonderful things in there and for these we made a bee-line. As much as I enjoy recording meetings it was refreshing just to be able to walk somewhere with botanists without getting mired in recording all the plants one sees on the way!

Within the range the first species of interest was a weed, which I over-enthusiastically misidentified as the umbellifer Torilis arvensis (spreading hedge-parsley) on account of its hooked fruits. This is an endangered plant, severely declined in Oxon, and everyone got rather excited. Subsequent to the meeting I re-examined the plant and realised that it was instead Anthriscus caucalis (bur chervil), which also has hooked fruits. We all get things wrong sometimes, but this is still an interesting record! While not threatened A. caucalis has very few Oxon records, most of them old.

The author holding Anthriscus caucalis and looking pleased with himself despite being wrong

Peppard Common - a guest post by Jack Dorkings

Enchanter's nightshade

On the very sunny Tuesday after Mayday, the Chilterns Atlas Recording group met at a quiet crossroads close to Peppard Common (SU7081). This was my first outing to a recording meeting so I wasn’t entirely sure what to expect. I also forgot to bring my own notepad so I only logged a few of the species we found! The aim of the day was to record for the Atlas 2020 project.

Led by Sally Rankin, we covered a small patch of woodlands bordering the common. We found our first interesting plants here. Circaea lutetiana (Enchanter’s-nightshade, right) and Sanicula europea (wood sanicle). S. europea has been declining locally, so this was an important find, especially to see it in flower.

Moving on to the heathland, it was immediately noticed that there were several well developed patches of Ulex minor (dwarf gorse) present. The heathland area wasn’t especially large but did have characteristic species present, including Erica cinerea (bell-heather) mixed in with the gorse (left). In the clearing between the trees and gorse was dominated by grass, with tufts of Holcus lanatus (Yorkshire fog) surrounded with Festuca species Most likely F. ovina (sheep’s fescue) but difficult to verify in the field.

We moved onto an old disused golf course that makes up part of the common. There was a wide variety of wildflowers present here, including Cardamine pratensis (cuckoo flower) and Veronica chamaedrys (germander speedwell, below). Around this time, we were also lucky enough to see a stoat (Mustela ermina) run out from the forest onto the old golf course and run back again. Unfortunately it was too fast to get a picture! The golf course followed the slope of a rather steep hill, at the bottom were more wildflowers with a different mixture of species, including two more Veronica species found in close proximity, V. arvensis and V. serpyllifolia (wall and thyme-leaved speedwell).

Anti-clockwise from top: sanicle; dwarf gorse and bell heather; wall speedwell; germander speedwell; thyme-leaved speedwell

Unusual red cleavers

Our route for the day then took us through forest again to a wide mown area, bordering the forest with a large patch of Lamium album (white deadnettle). Rannunculus was abundant here, with all three common species (R. acris, R. bulbosus and R. repens). This mown area was bordered by a road and associated ditch, where Stellaria holostea (greater stitchwort) was found, alongside some interesting red Galium aparine (cleavers). This was said to be a stress response from the plant which can arise from mowing; given the broken stems this is probably the case. Interestingly this was the only small patch showing this, as there were other examples of G. aparine growing in close proximity that retained the usual green colour.

The last plant I took a note of was Galium odoratum (sweet woodruff). I initially confused this for more cleavers at a distance, but the flowers and smell (not to mention lack of barbs on the leaves!) gave it away pretty quickly.

I’m hoping to go on more recording trips in the local area in the near future — next time I’ll remember to take a proper notepad to take note of everything seen!

Somerton and the Oxford Canal

Botanists botanising by the Oxford Canal. Remark the use of modern technology. Image by Fay Banks

Recording for Atlas 2020 in Oxfordshire continues. The target of this Sunday's meeting was the county's most under-recorded 10km square, SP42. Earlier in the spring I wrote about a recording outing of mine in SP42 at Tackley, and this week the venue was the parish of Somerton in SP42Z, further north along the River Cherwell/Oxford Canal. There will be another meeting in SP42Z on 8th July at Bestmoor SSSI, when we will survey the huge population of the nationally scarce Oenanthe silaifolia (narrow-leaved water-dropwort).

Sporangia of P. interjectum x100, with few thick-walled (indurated) cells forming the annulus and two basal cells between this and the stalk

The five of us who met at Somerton were blessed with wonderful weather and some fabulous plants. We started at the churchyard of St James’ which was a tidy disappointment, however. An exhibitor at the church exhorted us to come in afterwards for coffee and artwork, but we conveniently forgot and instead went to the Bell Inn in Lower Heyford! The only interesting native species in the village was a large amount of the fern Polypodium interjectum (intermediate polypody) on a shaded wall. Contrary to previous records I am finding that this is a common fern of limestone walls in Oxfordshire. I’d be grateful if other recorders would check any Polypodium they find microscopically, or record it as P. vulgare sens. lat. rather than attempt an identification based on frond morphology as this is not reliable.

We left Somerton southwards across bright green agricultural grassland and wheat fields infested with Alopecurus myosuroides (black grass). At this point I began to worry about our species list. A short detour out of SP42Z into SP42Y gave us Senecio viscosus (sticky groundsel) by the railway, from where we looped back into our tetrad and picked up the Oxford Canal. From here our fortune turned.

The Joys of Becoming a Recorder

Fay Banks wanted me to communicate her discovery of the joys of becoming a botanical recorder — many thanks to Fay for sharing some of the things she has seen. If you'd like to become involved in recording plants in your local area or elsewhere in Oxfordshire then do please get in touch with me by email (david.m.morris1989@gmail.com).

I have only just started recording and am very inexperienced. If I am unsure or completely stumped David is ever helpful. I am enjoying every minute of it, and learned a great deal by accompanying David et al on the recording training at Waterend. The area I am covering is not wildly exiting being mainly arable farmland but it also includes several villages and stretches of the River Thame. I have also discovered lots of good walks and two local nature reserves about which I was unaware. To date I have found no rarities but I have a few favourites among the more common flora.

Goatsbeard (Tragopogon pratensis) found in Marsh Baldon Churchyard. I like this because you have to be out in the morning to see it. By noon the flowers close and walking past it just looks like grass.

Shining cranesbill (Geranium lucidum) forms a large clump on the verge of Windmill Lane in Wheatley

Common fumitory (Fumaria officinalis), growing on the Howe allotments in Wheatley.

Waterend and Beacon's Bottom

Botanists using the BRC's iRecord app to record bush vetch (right) growing on a road verge in Waterend.

The first meeting of the year is always an event to look forward to, and Sunday 23^rd was the first of the botanical recording meetings I will be organising this season. The meeting was based in Waterend, a small hamlet to the east of Stokenchurch (SU79), and was attended by seven botanists.

For the morning we were very kindly hosted by a member of the party, and tea was a welcome accompaniment to the serious matter of the meeting: the where, how and what of botanical recording! For this was no ordinary square bash, but an opportunity to learn in a more focused (I hesitate to call it structured) way how to go about gathering botanical records.  Ostensibly this was to provide help and encouragement to locals interested in recording for Atlas 2020, for which there is much to do in Oxfordshire, particularly in the Chilterns where the meeting was held.

Where a record is from is perhaps the most important piece of information attached to it, and gathered round the garden table in bright sunshine and with the Ordnance Survey map of SU79 spread before us we started at the very basics of how to read a map reference. Then, what is this mysterious talk of 10km (hectad), 1km (monad) and 2km (tetrad) squares that recorders deal in? The published Atlas 2020 will, like previous BSBI atlases, consist of dot maps at 10km resolution, so the importance of the hectad as the main recording unit was emphasized. We discussed how to approach sampling such a large area by means of tetrads: this is quite a lot of work and the discussion was tempered with a reminder that we are all volunteers and recording is supposed to feel fun. None of us who take on squares to record should therefore feel over-burdened by the responsibility, and contribute whatever we are able to or find interesting.

Weekend highlights

The hybrid violet Viola x scabra showing a mix of hairy and sweet violet traits, notably the hairy petioles and presence of stolons, respectively.

I'd really like the Oxfordshire Botany blog to be a place for local recorders to share their interesting finds and experiences whilst recording. As the recording season is definitely now upon us I therefore thought I'd start with some reflections on my weekend out botanising. Please do let me know if you would like to do a write-up for the blog in future.

One of my main recording objectives for this year is to get the hectad SP42 up to scratch: as one can see on the Atlas 2020 page it is a very under-recorded part of the county. I made a start on that objective this weekend by recording around Tackley in the south-east corner of SP42. Nobody seems to have recorded there since the 1960s, not for the BSBI anyway. The two tetrads that cover most of Tackley (SP42Q and SP42V) have a good mix of habitats, with the village, to the east the River Cherwell, its floodplain and the Oxford canal, a Local Wildlife Site (LWS) in SP42Q and two in SP42V, and large and small woodlands scattered through mixed farmland in the area. Given this diversity of habitats, semi-natural and artificial, I felt the area was a good one to choose as part of my recording of SP42. I mostly focused this weekend on SP42V but the churchyard of St Nicholas' in SP42Q looked enticing and so I recorded there also. Of the local wildlife sites, Tackley Heath (SP42Q) and Crecy Hill are open access, which is useful, and a public right of way passes through part of Northbrook Marsh.

Vernal Violets

Last week I received my copy of the BSBI's new handbook Violas of Britain and Ireland, by Mike Porter and Michael Foley. It's a pretty little photographic guide, and as it's the time of year for many violets I thought a blog post would be apposite. I hope it prompts a few readers to buy a copy and/or to have a closer look at the violets growing around them.

In Oxfordshire we have ten of the fifteen UK Viola species and six of the eleven hybrids. The species have been variously divided at subspecies and variety level but these have not traditionally been recorded in the county, or records are only of the nominate species (e.g. Viola tricolor subsp. tricolor). The other infraspecific taxa tend to be found in habitat types that we don't have (e.g. the dunes favoured by Viola tricolor subsp. curtisii), but four of the at least six varieties of the sweet violet Viola odorata have been recorded. I will just talk about the eight taxa (five species) I have found around Islip - were I to venture to Otmoor then I'd be able to add a few others, such as the rare fen violet Viola persicifolia.

As quite a large genus by British standards it is best to start by dividing the species up into groups: first the pansies and violets, and then subdivisions of the latter. This is how all the keys work and is easy to remember.

Blysmus intervention

Blysmus compressus grows in only one place in Oxfordshire (V.C. 23), in Old Marston within the complex of meadows and floodplain grassland along the River Cherwell designated as the Almonds Farm and Burnt Mill Meadows Local Wildlife Site. The population of Blysmus is quite healthy, extending over about 30m of the bank and with  thousands of inflorescences produced last summer. However, its future has been uncertain for several years with the cessation of grazing following the lapse of the previous tenancy and there has been no management for the last six years.

Not any more! This last weekend volunteers mowed the bank on which Blysmus grows in order to set back the coarse sedges and grasses beginning to overwhelm the smaller plants requiring shorter, finer vegetation, Blysmus included. Without this cutting Blysmus will eventually disappear under a thatch of coarse grasses and sedges, joining the list of Oxfordshire's extinct plants. Repeated again toward the end of summer and again in future seasons this management should result in a diverse sward of herbs and short sedges, just as it ought to look!

Many thanks to the volunteers who helped with this conservation intervention, to the owners Oxford City Council for their permission and assistance, and to the tenant farmer for his permission and sympathy for the cause of this threatened plant. Judy Webb who helped to organise the day has put some excellent photos and videos of scything in action on her website — except for the clothes and the kind of scythes used, the scene could be medieval.

Vegetation supporting Blysmus at Marston, dominated by grasses and with abundant Equisetum arvense and Potentilla anserina. According to results of the Threatened Plants Project the latter is a common associate of Blysmus compressus.

Sibthorp Digitization Project

Sibthorp’s

Flora of Oxfordshire

  Translation and

  digitization project

Otmoor Stoneworts

Do you know what a stonewort is? Did you know that in addition to vascular plants (i.e. flowering plants, conifers and ferns) the Botanical Society of Britain and Ireland (BSBI) also collects records of stoneworts? I suspect that for some recorders the answer is 'no' to both. Stoneworts are a lovely, if obscure, group of aquatic green algae, but one could be forgiven for thinking they were some sort of weird vascular plant. Too big for proper phycologists, the BSBI seems to have adopted them out of sympathy.

I'd be really thrilled to receive any records of stoneworts from the county. If you feel like having a go then there's an excellent key to the commoner plants available from the BSBI here.

The Otmoor area has a lot of ditches and ponds, and it is not very difficult to find stoneworts round here. Indeed the moor is well known as an historic hot-spot for the nationally rare Tolypella intricata (tassel stonewort), recorded from the Saxon pond known as the Pill on Otmoor as well as a small number of ponds and ditches around the edge of the moor. The status of T. intricata is rather perilous nationally and around Otmoor owing to lack of pond and ditch management, and probably eutrophication, and it is listed as Endangered by the IUCN and is a species of principal importance (former UK BAP). The last report I know of it is from Nick Stewart, the national charophyte expert, who surveyed Otmoor for it in 2006 for the RSPB, finding a few plants in Greenaways on the reserve. I couldn't find it in 2016, but I was rather late — T. intricata gets going in March before aquatic vascular plants can grow up to out-compete it. The Freshwater Habitats Trust have been trying to rescue the plant, collecting soil (and, they hope, spores) from an historic Otmoor site for T. intricata and translocating it to ponds at the BBOWT reserve at Gallows Bridge Farm in the upper Ray, just within Bucks (V.C. 24).

Tolypella glomerata growing in a clean new ditch. The clusters of fertile branches give the species its name.

This weekend I thought I'd have a search for T. intricata in another Otmoor locality, Mansmoor in the parish of Charlton-on-Otmoor, to the north-west of Otmoor. Druce knew it from a ditch along Mansmoor Lane, which is now a dead end ending in the new railway. The area is anciently enclosed common land and most is a SSSI, including BBOWT's Wendlebury Meads, renowned for its ancient grassland. Sadly I didn't find T. intricata (the ditches were revolting), but I did find a stonewort almost as exciting: the nationally scarce T. glomerata. For some reason there are no records of this from Oxfordshire in the BSBI database or the NBN, but I know it has been recorded from the county, at least from Otmoor.

For this pretty little stonewort we have Chiltern Railways to be thankful, believe it or not. Although to build their new railway they had to clear many kilometers of hedgerow, an awful lot of new drainage has been constructed and many of these features now support stoneworts. My Tolypella was in a shallow surface water lagoon adjacent to the new bridleway over the railway from Mansmoor Lane, and which is now the main foot route to Wendlebury Meads. There were quite a number of plants scattered along the length of the lagoon. Where did the spores come from? Might T. intricata be in there somewhere too? You can be sure that I'll be looking for it.

Atlas 2020

This is a very brief post to advertise a new page on Atlas 2020 that I have finally finished tweaking (read: faffing about with) – see 'Atlas 2020' under the 'Recording' tab or click here. The spur to get it done came from the successful and highly enjoyable Thames Valley Environmental Records Centre recorders' conference held in Wallingford this last weekend. I gave a brief update on recording progress for the Atlas and following conversations with other recorders thought it was about time I gave the Atlas more prominence.

The new page does several things:

• Outlines what Atlas 2020 is about.
• Summarises my views on progress to date with Atlas recording in Oxfordshire (VC 23).
• Provides some thoughts for future work with Atlas recording in order to get the county up to scratch by the end of 2019.
• An interactive map showing the county, its tetrads and hectads, and how many taxa have been recorded and other statistics about each square.

I hope that the above will be of interest and use to recorders, both seasoned and prospective. As ever, do get in touch with me if you would like to be involved or want more information.