Atlas 2020, c'est tout finis

As you may have noticed, we are no longer in 2019, meaning that my favourite blog post topic, the BSBI's Atlas 2020 project, is finished. I have been meaning to write something to mark the occasion and celebrate everyone's hard work, but appallingly have been preoccupied with bryology and numerous other things this winter. However, I currently find myself becalmed in an Essex hotel, so here are some concluding thoughts on Atlas 2020 in VC23.

First, it has a been a great pleasure to receive everyone's records over the last three and a bit years. Seeing what local botanists have been up to has been very interesting and enjoyable, particularly being able to share in the excitement of unusual discoveries. I have had records from a relatively small number of regular contributors, either individuals or group recorders, some of whom have produced a considerable volume of records, as well as less frequent recorders. Many of the records that have come through me have been by email, but over the summer of last year the BSBI Distribution Database made friends with the iRecord database which gave me access to the 12,000 or so records from that source. Many of the iRecord records have been collected by a greater diversity of people than belong to the quite small circle of botanists associated with our local flora groups and the BSBI.

It is invidious of me to mention names, but special thanks must go to Tim Harrison, Jonathan Shanklin and Pete Stroh, none of whom live in the county (Jonathan and Pete live as far away as Cambridge and Peterborough, respectively) but who nevertheless spent a lot of time thoroughly surveying under-recorded areas of VC23. From the locals, we have also had regular and significant contributions from Sally Abbey, Fay Banks, Nick Barber, Brenda Betteridge, Susan Erskine, Renée Grayer, Sue Helm, Roger Heath-Brown, Frank Hunt, Clare Malonelee, Oli Pescott, Sally Rankin, Ruth Ripley, Barbara Spence and Frances Watkins. Judy Webb has been very helpful in sending me lists from her prodigious site monitoring work. Of course, as described in a previous blog, a huge contribution to the county's vascular plant data holding comes to me via my data sharing agreement with TVERC. I am very grateful to their data officer Ellen Lee for organising this, as well as to the many recorders who submit their records to TVERC, whom I am sure would be pleased to know that their records contribute to national recording projects like Atlas 2020.

Atlas records per year, excluding duplicates. Red lines are yearly number of records, on the left vertical axis, and blue lines the cumulative total, on the right. Solid and dashed lines are numbers of records with and without TVERC records.

Overall, the records gathered between 1st January 2000 and 31st December 2019 number a little over 320,800 (excluding duplicates). You can see how the records were accumulated in the graph to the left. This total is similar to most other English vice counties, being a little more than the median (~305,200) and less than the mean (~336,100). I have verified all of the Atlas records for VC23, confirming about 330,000 records (including duplicates). Questions marks remain over around 1,200, but thank you if you helped me resolve any queries.

I have shown the split between records from TVERC and other sources to highlight the importance of our data sharing agreement, which makes up more than half of the total records for Atlas 2020. This agreement with TVERC has provided a steady stream of records each year, particularly from important privately owned Local Wildlife Sites, contrasting with the more stop-start contributions direct to the BSBI. What is evident from the graph is the late start to systematic recording of the county for the Atlas project, which began I believe when Sue Helm took on the county recorder job and Atlas recording meetings were first organised. Many thanks to Sue for her hard work during her three year tenure as recorder. The spikes and troughs in the later Atlas period reflect the comings and goings of the non-VC23 based botanists thanked above.

In terms of spatial coverage and success, the county can be pleased with its Atlas dataset. This is summarised in the series of maps shown, which are stills from my interactive Atlas webmap. The project was never supposed to be a complete survey of every tetrad (2km square) in the county, but a repeat of previous hectad (10km square) national atlas surveys, based on a sample of tetrads. The re-recording rate (the coloured proportion of grid squares in the maps) is the crucial statistic for measuring progress — while there have definitely been changes to our flora, most species will still be present in most squares, so the higher the re-recording rate the more thorough and representative the sample is. The BSBI advised that a hectad re-recording rate of 70-80% should be aimed for, and this has been met for many hectads, and just about all compared to the recording period for the New Atlas (1987-1999). On the other hand, since we have no way of measuring abundance, records from too thorough a search might belie real declines, with for instance a formerly common plant reduced to a single plant both registering as present in the Atlas.

The above picture is somewhat complicated by recording effort over different periods and across taxa. The most intensive and extensive period of recording in the county was for the 1997 flora of John Killick et al, recording for which was largely complete by the late 1980s. In contrast, the New Atlas period saw less intensive recording than for the flora and the current atlas project. The difference between native and alien plants also obscures the picture, as many aliens are casual or sporadically recorded. This is well illustrated by the hectad with the city of Oxford (SP50), which has historic records of very many alien taxa from the city's old tips and waste ground. I will let the boffins at BSBI and CEH ponder how to deal with all these complications!

Drilling down to a scale more relevant to local recording, the tetrad coverage was good, indicated by the distribution, colour and size of the tetrad squares in the map shown. There were some solidly recorded areas, especially in the centre of the county, with effort thinning out to the south-east and north-west. Tim Harrison was a great help in improving several hectads in the south-east. The good results for the centre of the county doubtless reflect the very rich and varied sites around Oxford, but some recorder bias is clear, these sites also being much more accessible than in more remote areas (many are nature reserves) and this is where most of the botanists live. This includes myself, and Islip where I live (SP51H) stands out as among the most species-rich tetrads in SP51 together with the unimproved part of Otmoor (SP51R). In fact, Islip is fairly unexceptional compared with most of the nearby parishes (although there are two rivers) and many of the species I have recorded are garden escapes.

Summary of Atlas 2020 results in VC23, by hectads (top) and tetrads (bottom). The colour of grid squares is the number of species recorded (as shown in the legends), and the proportion of the coloured area is the proportion of species re-recorded from the comparison period (i.e. 1987-1999 or pre-2000). The tetrad map compares atlas records to all pre-2000 records.

After having worked so hard on Atlas, I am sure like me you are ready and rearing to start the next project. The BSBI has not yet announced the projects the society will work on over the coming years. However, it is likely that it will be something more ecology or conservation focused than Atlas 2020, for instance habitat surveys or developing site lists and registers. Myself, I'd like to direct some focus on data deficient taxa, but will be continuing the tetrad recording. The meetings I will be running this year will combine elements of these and less intense training sessions. I've already put dates in the calendar for this season — if you'd like to join me and are not already on my mailing list then do get in touch.

Atlas recording in Sutton

After a pretty ordinary Atlas recording session a fortnight ago, on Sunday we had a return of luck and the big lists of earlier in the season. Expecting again ordinary countryside around Sutton (SP40D), we were rewarded with over 320 taxa, a list that included many interesting native plants but that of course was boosted significantly by garden escapes and other aliens. As last time, I will single out the native look-alike shrubs in the hope that this will generate more records and demonstrate that these things are ubiquitous (last time we were far away in SP42F). Maybe I should put together a key to these things — if you'd find this useful or interesting then leave a comment below and I might consider it!

If you look in the floras and the literature about native look-alikes, you'll see that there is an alien taxon for just about every native hedgerow and woodland shrub in Oxon, and some, like the dogwoods I blogged about last time, have several. This meeting it was the turn of the guelder roses, a commonly planted hedgerow shrub (entirely inappropriately, the native Viburnum opulus being largely a plant of damp woods) and of which Sell and Murrell describe two non-native forms of the native species and two similar alien species. My practice had been to lazily assume that planted things were at least the native species, if perhaps cultivars, but confronted with strange-looking plants in the Sutton area I had to revisit this assumption. The native guelder rose is an elegant plant with quite thin yellow-green small and neatly toothed leaves — if you see anything with thicker or darker or larger leaves with strange shapes then consider V. sargentii (Asian guleder-rose) and V. trilobum (American guelder-rose). I think we had both on Sunday, new to the county but doubtless overlooked elsewhere. V. trilobum has odd-looking thick-stalked glands on the petioles (I had never even noticed that guelder roses had glands!) and the leaves on the upper parts of branches have the middle lobes longer than wide. V. sargentii is similar to V. opulus with sessile glands and the middle leaf lobes as long as wide or less, but the leaves are thicker and darker and less toothed (some other differences are also described in Stace and Sell and Murrell).

Continuing with aliens, but aliens we botanists are prepared to tolerate and even admire, we also had a good variety of arable weeds. A fallow field sported no fewer than five species of Chenopodium, with the common C. album (fat-hen) and C. polyspermum (many-seeded goosefoot), the less common C. rubrum (red goosefoot) and the quite scarce C. ficifolium (fig-leaved goosefoot) and C. hybridum (maple-leaved goosefoot). We also had Euphorbia exigua (dwarf spurge), both species of Kickia (fluellens) and the fairly rare Polygonum rurivagum (cornfield knotgrass). I wouldn't be surprised if the latter were a little under-recorded — look out for its eye-catching dark pink tepals and narrow leaves (sorry for not taking a photo).

We did quite well for aquatic plants too. A new pond had Potamogeton crispus (curled pondweed) and P. berchtoldii (small pondweed), and the aquatic liverwort Riccia fluitans which I had never seen in Oxon. Other waterbodies turned up Zannichelia palustris (horned pondweed) and four species of Lemna (duckweeds).

I can't touch on aquatic plants without announcing Judy Webb's excellent pondweed find last year, and which I visited last week because I couldn't quite believe it. I shall deliberately not reveal the exact location of the site, but it would be hard to believe that just about any location in Oxfordshire would be suitable for Potamogeton polygonifolius (bog pondweed) these days. A plant of acid waterbodies and wetlands, it was known once-upon-a-time from Shotover Hill and a small number of other sites with the acid geology that is rare in the county, but had not been seen for decades. Yet there it was, growing in a former limestone quarry with plants of mineral-rich wetlands, like Schoenoplectus tabernaemontanii (grey clubrush) and the moss Campylium stellatum. The national pondweed referee Chris Preston was sensibly circumspect in not confirming the identification from my photographs, but I am happy to announce it now and possibly be proven wrong!

All of the above shows how dynamic our flora is, perhaps a theme of many of my posts on this blog. With people constantly disturbing and changing the environment and many plants good at dispersal and able to take advantage of this (naturally or because we find them attractive or otherwise useful), it is important and fascinating to record these changes and underscores the value of projects like Atlas 2020. So, please keep those records coming!

Recording at Glympton

A highlight of the BSBI ASM, Polygala amarella (dwarf milkwort)

It has been over a month since I last blogged and amazingly that was the last time I organised a meeting and did any serious recording in Oxfordshire! I have been botanizing, of course, with a highlight being the BSBI's Annual Summer Meeting which you can read about on the News and Views blog, including posts from yours truly. It might not have contributed to Atlas 2020 in Oxfordshire but it was awfully fun and will have made a big difference to Mid-West Yorkshire which needs records more than we do!

Anyway, this last Sunday I finally managed to find some time in the diary for a recording meeting, and I met up with three other locals at Kiddington. Just in time I had been reminded by Sally Abbey that her recording group had already been there this season, so rather than repeat their work we recorded a tetrad to the east of Kiddington, taking in the lanes, farmland and woodland of Glympton (SP42G). It was a fairly ordinary square without the many lovely highlights of previous meetings this season, but we hit the target of 200 taxa that makes me feel like it was worth going out. A few odd things were found, mostly plants that are likely under-recorded.

One such was the hybrid bindweed Calystegia sepium x silvatica (=C. x lucana), which I am not sure I have ever noticed before. Apparently it is a variable hybrid, but our plants had large flowers like C. silvatica (large bindweed) but with the bracts below the flowers only slightly overlapping and not pouched (as they would be in C. silvatica), and the leaves small, intermediate in shape between C. sepium (hedge bindweed) and C. silvatica (the latter has a broad sinus with a truncate base, the former a narrow sinus with an acute base, as illustrated in Polland and Clement). Another odd plant was Bromus commutatus var. pubens, which looks all the world like the usual meadow brome (var. commutatus) but has shortly pubescent spikelets. As I have described in previous posts, B. commutatus is likely a common cereal weed in Oxon but is significantly under-recorded, probably because botanists think of it as a plant of meadows.

Finally, something must be said about the hedges in the Glympton area, as they were the worst I have seen in Oxon for in-filling and re-planting with alien shrubs sourced from nurseries that should know better. Mile upon mile was full of non-native dogwood and spindle and questionable field maple and hawthorn, presumably on land belonging to the same estate. The dogwood which was the main component of many hedges was a great beast with enormous leaves — I think it was Cornus koenigii (Asian dogwood), a first for the county, rather than the more usual C. sanguinea subsp. australis from south-east Europe and which also often has large leaves. It'd be marvelous if other recorders could be mindful of alien shrubs in hedges and send me records. Planting these shrubs for housing, roads and other developments as well as countryside hedges has become very common and could come to affect our native scrub vegetation, so we need the records to understand potential future change. To encourage records, here's a key to Cornus taken from Sell and Murrell Volume 3.

1.	Hairs on underside of leaves mostly curved upwards and basifixed *	2
1.	Hairs on underside of leaves mostly adpressed and medifixed **	3
2.	Leaves 4-9 x 2-6cm	C. sanguinea subsp. sanguinea
2.	Leaves 5-13 x 2.5-7.0cm	C. koenigii
3.	Leaves with 2–4 pairs of veins; drupes black	C. sanguinea subsp. australis
3.	Leaves with 4–7 pairs of veins; drupes white or bluish ***	4
4.	Twigs bright yellow or bright red in autumn and winter	5
4.	Twigs becoming dark brownish-red in autumn	6
5.	Twigs becoming bright yellow in autumn and winter	C. alba var. flaviramea
5.	Twigs becoming bright red in autumn and winter	C. alba var. sibirica
6.	Plant not stoloniferous; leaves 5–15 × 3–10 cm	C. alba var. alba
6.	Plant stoloniferous; leaves 4–9 × 2.5–6.0 cm	C. sericea

* Bend the top of the leaf over your finger and hold it up to the light - you will see the hairs sticking up. Under a lens the hairs look like they have one arm, or if there appear to be two it is two hairs arising from the same point rather than a single medifixed hair.
** Bend the top of the leaf over your finger and hold it up to the light - you will see no or few hairs. Under a lens the hairs look like they have two arms, with both mostly pressed against the leaf.
*** The two remaining species look very different from the previous three and populations are usually very obviously of horticulutral origin, e.g. landscape plantings, garden rubbish. C. sericea can be invasive of damp woodland.

Rousham and Oxford Canal

Equisetum x litorale with the tall wide stems of E. fluviatile and whorled filiform branches of E. arvense. O.L. Pescott.

Another haul of excellent records from this weekend, when we were out botanising again in the north of the county. This time we returned to the Cherwell valley and Oxford canal in SP42, where a few meetings were held back in 2017. We met at the church on the Rousham estate, the plan being to quickly look round the churchyard and then head east to fill in a blank square (SP42W) along the canal. However, having parked in a silly place and been confronted by the farm manager, we were very kindly invited to some unplanned botanising of private parts of the estate — how could we resist? Although in the opposite direction and a different tetrad to that planned, it turned up some good wetland plants, including

Dactylorhiza praetermissa

(southern marsh-orchid) and the diminutive pondweeds

Potamogeton pusillus

(small pondweed) and

Zannichellia palustris

(horned pondweed). We also found the hybrid horsetail

Equisetum arvense x fluviatile (=E. x litorale)

(shore horsetail), which as far as I know hasn't been recorded in the county since 1982.

Having bumped up the tetrad records from Rousham (SP42S) and nearby (SP42R), we marched off to Lower Heyford to pick up the canal. Passing through the station (SP42X) we came upon an acquaintance from a previous meeting in the Cherwell valley, another hybrid, the dock

Rumex conglomeratus x obtusifolius (=R. x abortivus)

. The dense widely branched leafy infloresence was eye-catching and the tepals were intermediate in shape. Not a beautiful plant, but attractive in a Rumex sort of way. Surely under-recorded, this is one to look out along our river floodplains.

The Oxford Canal was productive for a range of common wetland plants. Although churned up by boats, the vegetation is less eutrophic than most of our rivers, with plants such as

Carex paniculata

(greater tussock sedge) common along the canal. Wet woodland and damp grassland by the canal provided more

C. pseudocyperus

(cypress sedge) and hundreds of

Dactylorhiza fuchsii

(common spotted-orchid). We had more hybrids, with the willow

Salix caprea x viminalis (=S. x smithiana)

and the woundwort

Stachys x ambigua

. Great to find the latter again this season after we had it at South Newington in May — with very few recent records could it be under-recorded?

The highlight from the canal was

Potamogeton lucens

(shining pondweed), growing in quite a large colony with the much commoner

P. pectinatus

(fennel-leaved pondweed). Always exciting to find a good Potamogeton and catch a glimmer of the former glory of our waterways. Thanks to Oli (pictured left) for being well-equipped with homemade grapnel.

By the end of the meeting I think all our legs were feeling tired, having walked back and forth through five tetrads. With our efforts divided we didn't get the impressive tetrad totals of previous meetings but we gathered over 500 records. Having seen more than 330 taxa the plants were certainly worth the mileage.

Broughton Casttle

The first meeting of June and the fifth of the season was held last weekend at Broughton Castle near Banbury. This site had been recorded previously for Atlas 2020 but we had special permission to botanise the whole park and therefore hoped to refind some of the plants historically recorded but not seen since 2000.

I had particularly hoped that we might find some of the nice aquatic plants that had been recorded from the Castle Moat. As it turned out the moat was a brown soup with very few macrophytes, an unpleasant appearance completed by floating dead freshwater mussels. The Sor Brook was no better, sporting also the invasive non-native aquatic plant

Egeria densa

, the first reported sighting of this plant in Oxon for 35 years. Tributaries of the Sor Brook had some other infamous beasties, with

Fallopia sachalinensis

(giant knotweed) and its giant handkerchief-like leaves and

Heracleum mantegazzianum

(giant hogweed). On a positive, we did find quite a lot of

Ranunculus fluitans

(river watercrowfoot), which was good to see.

Elsewhere in the park plant diversity was quite limited. There was a decent stand of calcareous grassland with plants like

Cirsium acaule

(dwarf thistle),

Koeleria macrantha

(crested hair-grass) and

Helianthemum nummularium

(common rock-rose), but these had all been recorded previously. In all we managed to find about 250 taxa, bumping up the tetrad total to 338 from 252. Not the enormous haul of records of previous meetings, but eminently respectable and goes to show that even in well-recorded tetrads there is always more to find.

Interesting things have been turning up elsewhere in the county this spring. I was contacted independently by Frank Hunt and Andrew Lack after they both found a new population of

Scandix pecten-veneris

(shepherd's-needle) near Sandhills, north-east of Oxford. Frank also found a new population of

Montia fontana

(blinks), surprisingly at the well-botanised North Leigh Common. This time of year always produces some sore heads when the marsh orchids come out, and surveying a meadow in the VC 22 part of modern Oxfordshire Judy Webb and I found what with the help of BSBI Dactylorhiza referee Ian Denholm we determined as a swarm of

D. maculata

(heath spotted orchid),

D. praetermissa

(southern marsh orchid) and their hybrid D. x hallii. The latter was new to VC 22 and the modern county.

Botanising less obviously delightful places for Atlas 2020 near Adderbury, I found

Viola tricolor

(wild pansy) and, along the Oxford Canal,

Lepidium heterophyllum

(Smith's pepperwort). According to the Flora of Oxfordshire the latter has not been seen in the vice county since 1983! Not far away was possible Galium parisiense (wall bedstraw), but I want to check the fruits to be sure. This has not been seen in Oxon before, but was recently found new to Northants (VC 32), in the VC 32 part of Banbury and elsewhere.

The excellent Oxfordshire's Threatened Plants published last year reported that the small annual

Minuartia hybrida

(fine-leaved sandwort) had gone the way of many such plants and was extinct in Oxon. Fortunately not so, as the population known historically from the old chalk pit in Chinnor is still there, found by Paul Stanley back in 2013 and also seen by Oli Pescott, David Roy and myself while recording around Chinnor. The old pit has many other interesting plants, so do go and see this little delight while it is still out.

The Barfords

Carex rostrata (bottle sedge) growing in an artificial pond

Sunday continued the run of highly successful Atlas 2020 recording meetings in north Oxfordshire, when as a a fortnight ago we had another haul of 300+ taxa. Three of us met at Barford St Michael, downstream along the River Swere from where we last met, but it was a disappointing start, the churchyard of St Michael's proving among the dullest I have yet visited in Oxon. We later visited St John's in the same tetrad (SP43G), but it was even worse. However, we did find a single plant of

Rumex pulcher

(fiddle dock) in St John's churchyard, identifiable despite having been mangled by mowing, and last recorded there in 1989.

This tetrad was on my list of priority squares for Atlas 2020, with almost no post-2000 records and several locally rare plants reported in the Flora of Oxfordshire that are the only historic localities for these plants in the hectad (SP43), e.g.

Carex rostrata

(bottle sedge) and

Triglochin palustris

(marsh arrowgrass). As with previous meetings, therefore, the goal was to fill in this gap in the tetrad map and re-find plants for the hectad. As other recorders have found, relocating old records can be very difficult, with most records from the Flora available only as digitised card indexes with no locality information other than tetrad or hectad. Therefore, do remember that in order that future botanists do not have to share in this frustration, it is important that if you find a plant that is uncommon in the county, or even just within the tetrad you are recording, that you record a precise locality.

I had not realistically expected that we would refind many of the rarer plants, and as we were not spoiled with habitats as wonderfully plant-rich as last time, serious leg work was required to cover as much potentially productive ground as possible. As last time most of the good habitat was located along the River Swere, particularly a small area of wet grassland around a spring, home to the Triglochin we sought, as well as other wetlands plants such as

Caltha palustris

(marsh marigold),

Stellaria alsine

(bog stitchwort) and

Valeriana officinalis

(common valerian). The nearby floodplain of the Swere had

Carex nigra

(common sedge), also on my hectad wanted list,

Myosotis discolor

(changing forget-me-not) and other commoner floodplain plants.

I had assumed that the historic record of

Carex rostrata

would have been from the floodplain also but doubted there would be anywhere wet and unpolluted enough to still have it. As it was it we turned it up growing in abundance in a pond formed by damming of a small tributary of the Swere. Where did these plants come from? Willows along the edge of the pond, however, had clearly been planted, and included several quite large specimens of

Salix pentandra

(bay willow), a rare willow in Oxon and also on my hectad wanted list. Growing in pasture nearby was a bedstraw that had the habit of

Galium album

(hedge bedstraw) but with leaves on the narrow and suspiciously parallel side for this species — surely, the hybrid with

G. verum

,

G. x pomeranicum

? Some came home with me to see if it will produce the intermediately-coloured flowers that would clinch this determination. Although records indicate that it has always been rare in the county, do keep an eye out for this distinctive plant in meadows and pasture on calcareous soils.

A couple of closing thoughts on other harder to identify plants. Now is the best time of year to find and identify members of the

Poa pratensis

aggregate, with both

Poa angustifolia

(narrow-leaved meadow-grass) and

Poa humilis

(spreading meadow-grass) recorded on Sunday. Though quite distinctive plants (especially

P. angustifolia

) they are only really obvious in spring and early summer after which they are swamped by taller things — see the Plant Crib for descriptions. Finally, roses will be coming into flower over the next couple of weeks and one can start to provisionally put names to bushes (e.g. we had

Rosa obtusifolia x canina

on Sunday). It would be really great to have some more rose records for Atlas, so if you find a rose that might be a bit different (mainly things with glands and hairs) then do take photographs and I can provide some advice — the things to look for are summarised in the BSBI Yearbook under the referees section or in the roses handbook. You can see what roses have been recorded in your area by looking in the tetrad lists available via the Atlas progress map.

Note: The next meeting will be on June 1st, which is a Saturday rather than the usual Sunday. We have been given permission to explore the grounds of Broughton Park — please email me if you would like to come along.

South Newington

Note: I have added a new function for the blog — hover over a species' scientific name to see a map of its current tetrad distribution in vice county 23. The data come live from the BSBI Distribution Database.

Above: grassland on the valley slope above the River Swere, with abundant Poterium sanguisorba. Several spikes of Carex caryophyllea are also visible. D. Morris. Below: Equisetum fluviatile and tussocks of Carex actua and C. paniculata growing in the pond. O. Pescott.

The numbers of botanists attending my recording outings continues to dwindle, with just Oli Pescott and myself meeting in South Newington last Sunday. However, what we lacked in people we made up for in plants, the tetrad (SP43B) yielding the richest crop of any recording meeting I have organised over the last few years. Meetings in this area continue to demonstrate that though this part of the Cotswolds may be far away for many of us it is well worth the journey (lifts can be arranged!).

As is traditional, we started with the local churchyard, unusually dedicated to St Peter ad Vincula, which proved to be among the better of those we have visited recently. Half of the churchyard had been left uncut and was covered in

Ranunculus auricomus

(goldilocks buttercup) and there were other typical churchyard plants such as

Leontodon hispidus

(rough hawkbit) and

Saxifraga tridactylites

(rue-leaved saxifrage). Exploring the village afterward, we had fun deciding whether members of the garden flora had gone sufficiently wild that we could record them — some such as

Geranium sanguineum

(bloody cranesbill) only just made it onto the list.

The River Swere meanders through South Newington, and the valley of this small tributary of the Cherwell north-west of the village provided a feast of native plants. We spent several hours exploring a fabulous meadow in the main valley and a wooded valley of a tributary to the north (both accessible by footpaths). The meadow sported an abundance of wildflowers, including drifts of

Conopodium majus

(pignut),

Geranium pratense

(meadow cranesbill) and

Poterium sanguisorba

(salad burnet), and numerous local species such as

Avenula pratensis

(meadow oat-grass),

Carex caryophyllea

(spring sedge),

Hypericum maculatum

(imperforate St John's-wort) and

Polygala vulgaris

(common milkwort), of which C. caryophyllea and P. vulgaris were new for the site and on my Atlas 2020 hectad wanted list. There were numerous other sedges in the meadow, particularly in a former course of the Swere, where we found

C. actua

(slender tufted-sedge),

C. acutiformis

(lesser pond sedge),

C. paniculata

(greater tussock-sedge) and

C. riparia

(greater pond sedge).

Exploring the valley to the north, we found large colonies of

Scirpus sylvaticus

(wood club-rush) along a stream and around springs, as we did earlier this spring.

Neottia ovata

(common twayblade) was on my Atlas 2020 wanted list for the hectad — it had not been seen in this tetrad before but the site looked suitable and we managed to find a single plant. Some other highlights included

Salix purpurea

(purple willow), another new species for the tetrad, and the hybrid woundwort

Stachys palustris x sylvatica (=S. x ambigua)

, which I had never seen before but which Oli knew from up north where it is more common. There are hardly any records of S. x ambigua from Oxon, so this was a particularly good record.

I had aimed to visit another site but I forgot how to get there, but exploring the lanes of South Newington turned up further nice plants such as

Helianthemum nummularium

. The site would have added a few more species to our list but as it was we returned to South Newington with a list of over 300 taxa and very happy botanists! The tetrad is now very well recorded and we recorded several species that can be really quite difficult to relocate once they have been missing from a hectad for some time, so an excellent contribution to Atlas 2020.

Scirpus sylvaticus. O. Pescott

Bloxham Atlas recording

It's already time for me to write another blog post about another Atlas recording meeting, held last Sunday. With fortnightly weekend meetings (listed in the events calendar), can I keep this up all season?

Sunday's meeting was in an even further flung corner of the county than the previous meeting. Three of us met at St Mary's church in Bloxham (SP43H), a rather grand edifice for a parish church. The churchyard further confirmed my experience that unimproved but heavily mown churchyard grassland in Oxon is characterized by a small number of hangers-on, species like

Leontodon hispidus

(rough hawkbit),

Plantago media

(hoary plantain) and in spring often

Ranunculus auricomus

(goldilocks buttercup). It was perhaps a little early in the year to be absolutely confident of the potential

Epilobium lanceolatum

(spear-leaved willowherb) which Oli Pescott found — definitely worth a visit later in the year to verify whether it was this locally rare willowherb. After the church we botanised the local streets, picking up spring annuals like

Saxifraga tridactylites

(rue-leaved saxifrage) and a host of garden escapes, such as the unusual

Geranium x magnificum

. We also found

Petroselinum segetum

(corn parsley), which is not that uncommon around Oxford but which hasn't many recent records from the north of the county.

In addition to its being hardly recorded, the main attraction of SP43T had been The Slade, a former BBOWT nature reserve and now an official Local Nature Reserve (LNR) managed by the parish council. This spring-fed site had once supported such wetland delights as

Molinia caerulea

(purple moor-grass), so although these had not been seen at the LNR for a long time it nevertheless looked enticing. We did not succeed in refinding any old wetland rarities but did turn up

Dactylorhiza fuchsii

(common spotted orchid),

Hypericum maculatum

(imperforate St John's-wort),

Silene flos-cuculi

(ragged-robin) and a lot of Rosa arvensis x canina (=R. x irregularis). This hybrid rose is very distinctive when growing in sunny places: looking like R. arvensis (field rose) on speed, it forms dense and often very extensive thickets with more robust stems than is usual in R. arvensis and many of the hips are small, black and abortive. Possibly R. x irregularis is under-recorded as I find it quite often, usually in more open places than is usual for

Rosa arvensis

.

The last nice plants of the day came from some hands-and-knees work in very nibbled sheep pasture, where we managed to find some small patches of

Saxifraga granulata

(meadow saxifrage). It was not quite in flower but was nevertheless great to see. On the whole we had to work quite hard for our records, so I was surprised to find after entering the data that we'd recorded 253 taxa (albeit with quite a lot of aliens), putting the post-2000 total to 297 — a valiant effort!

The next Sunday recording meeting will be on 12^th May. It'd be great to have more botanists along — hopefully the last two blogs have shown that there are plants up in the north of the county worth travelling for!

Tetrad distribution of

And so it begins

The first recording meeting of the final season of Atlas 2020 in Oxfordshire was on Sunday. Meeting in Nether Worton in SP43, the location was evidently a little out of the way as there were only four of us, but if you thought that then you missed out on good botanising. Rather than the more usual square-bashing strategy, the aim of this meeting was to record an already quite well-recorded area in order to improve it further and also to pick up some plants that have not been seen this century in the hectad in Oxon, such as the woodland plants Viola reichenbachiana (early dog-violet) and Melica uniflora (wood melick). Previously these areas had been visited later in the year and we were therefore sure to pick up new things.

We started at the churchyard of the tiny church of St James' in Nether Worton (SP43F), a tetrad with a respectable post-2000 total of 168 but some missing vernal species. The churchyard was pretty undistinguished, with typical hangers-on of heavily-mown churchyard grassland such as Plantago media (hoary plantain) absent. There were plenty of naturalised non-natives to lend colour though, such as Cerinthe major 'Purpurescens', an annual bedding plant from the Mediterranean which appeared to have seeded from the adjacent garden and was a first for the county. There were also many plants of Ranunculus auricomus (goldilocks buttercup) here and in the nearby verges. We didn't stay long in the tetrad due to lack of promising-looking land accessible by footpaths, and instead headed west toward the Great Tew Estate via a detour north over Iron Hill Down (SP43A).

After a few kilometers on Iron Hill Down I was feeling pretty desperate as the place was an arable wasteland, though there were some springs with a few common wetland plants in one area. Crossing the B4031 south into the Great Tew Estate the spirits lifted, however, with a flurry of ticking of semi-natural woodland and grassland plants, like Sanicula europaea (sanicle) and Poterium sanguisorba (salad burnet). Thinking aloud I suggested that some nice grassland looked perfect for Ophioglossum vulgatum (adder's-tongue fern) and then promptly found several of the tiny fronds of this lovely vernal fern. Turned out this was a new hectad record!

Continuing into the valley bottom toward Great Tew we came upon a series of wet woodlands with springs and streams. Here we found a small population of Scirpus sylvaticus (wood club-rush), a scarce plant in Oxon. As a species of feruginous wet woodlands, this north-western part of the county with its iron-rich limestone is the main area where it has historically been recorded. The population we found was first seen in 2015. Some of the other highlights of this area included Polystichum aculeatum (hard shield-fern) and Hypericum maculatum (imperforate St John's-wort).

We concluded the meeting back in Nether Worton with a pretty diverse haul of records for early April. In total we collected 340 records of 236 taxa: 197 in SP43A and 127 in SP43F. This put the tetrad totals up from 214 to 284 in SP43A and from 168 to 214 in SP43F. Certainly better than I was anticipating after a pretty dismal morning! The next meeting will be on 21st April — I hope you can join me.

BSBI recorders' conference

I have just returned from a thoroughly enjoyable BSBI recorders' conference at FSC Preston Montford near Shrewsbury. The conference is one of the main events in the BSBI calendar, when vice county recorders, taxonomic referees, BSBI staff, active recorders and anyone else interested in the British flora come together to discuss topical botanical issues and learn yet more about plants. The conference this year was very much focused on training and the future of botany in Britain and Ireland, and there was much lively discussion around these. The many workshops included docks and willowherbs, Abies (firs), how to press plants, and introductions to critical taxa such as Taraxacum and brambles. The slides and training material from all the talks and workshops will soon be available from the BSBI website.

We had a useful update on Atlas 2020 from Pete Stroh, BSBI science officer, recent appointee to the new position of English officer and Atlas 2020 coordinator. Pete told us about the likely outputs of the Atlas 2020 project: a printed book, similar to the previous New Atlas; a smaller less dense publication summarising the findings; and an online format, similar to the existing online New Atlas but with greater scope for extra detail on distribution, ecology and conservation. He also set us the deadline of the end of December 2019 for all data entry and validation for Atlas 2020 — if you are sitting on records please therefore think about sending me them this winter!

Local botanists using the BRC's iRecord website or app to collect and store their records will be interested to hear about progress in linking the iRecord database with the BSBI's Distribution Database (DDb). Our own Oli Pescott of BRC gave a talk on iRecord, informing the audience that all being well the two databases will be talking to each other by the New Year. Records imported to the DDb from iRecord will be held in a 'quarantine' area from where they can be liberated by county recorders.

You would think that I might have some nice photographs of botanists conferring by which to remember this excellent event. Not so. Without apology, the only images I collected were of dead plants stuck to paper, and dead roses at that. I had taken with me a stack of Oxon's best and weirdest roses to subject to the scrutiny of the BSBI Rosa referee. I was very pleased to have confirmed specimens from Sydlings Copse Nature Reserve tentatively identified as Rosa obtusifolia x micrantha (third from left below) and R. micrantha x rubiginosa (=R. x bigeneris) (second from left below). Both are rare roses and new county records. The former is also at Aston Rowant, as reported last autumn. Also confirmed was R. sherardii x canina (=R. x rothschildii, first on left below) at the reserve, making it one of the best sites for roses in the county. The referee was less convinced by my several possible R. obtusifolia x arvensis (=R. x rouyana) (below right). A really odd rose that had completely stumped me also proved unnameable (right). Such intractable specimens are part of the fun and frustration of roses.

The next BSBI event is the Annual Exhibition Meeting on 17th November. Will you be coming along?

Botanising in Northants

The new recorders for Northamptonshire (VC32), Alyson Freeman and Brian Laney, have asked me to publicise botanical goings-on over the border this weekend. If you would be interested in joining them recording the Northants parts of Banbury this Sunday 30th and Middleton Chaney and Chacombe on Monday 1st October, then please contact Alyson via alysonfreeman0@gmail.com for further information. Unfortunately I cannot be there but it'd be good to have an Oxon contingent to support our neighbours in their recording.

Cottisford

The 2018 recording season is truly upon us, and Sunday was the first of several Atlas 2020 recording meetings I will be organising this year. The target was far-flung Cottisford, an area in the north of the county I had never been to before, and I was joined by four other keen botanists for a delightful day botanising in glorious spring weather. I had identified this square (SP53V) as a target for recording using the interactive Atlas 2020 coverage map available here. Although the tetrad had around 150 taxa recorded it still had a low recording rate indicating there was much else to find, so the aim of the meeting was to focus on species and habitats not covered by previous records: as these were focused on the Cottisford Pond Local Wildlife Site (LWS), there was plenty other ground to cover. Notable plants to look out for included Astragalus glychyphyllos (wild liquorice), last seen in 1993, and Carex elata (tufted sedge), last in 1968. Read on to learn whether we found either!

We started off in the churchyard in the village, St Mary the Virgin, where we had the usual lawnmower-tolerant species of unimproved churchyard grassland such as Plantago media (hoary plantain). There was a single rosette of Dactylorhiza fuchsii (common spotted orchid) and an abundance of flowering Luzula campestris (field wood-rush), an understated spring beauty. Making out of the village for the area where the Astragalus was last recorded we came upon a few patches of flowering Rancunulus auricomus (goldilocks buttercup) in a hedgebank. Further along were scraps of limestone grassland with an abundance of Cirsium eriophorum (wooly thistle) and a few plants of Lithospermum officinale (common gromwell), which was new the to square. Also new was Hypericum maculatum (imperforate St John's wort), relatively scarce in Oxon, and further up the lane we found the sought-after Astragalus, much to our delight. There were a mere five small tufts of this species growing in a rather unprepossessing verge by a farm track.

The next few hours were spent wondering along footpaths picking up records from a variety of habitats. Two large fields of Linum usitatissimum (cultivated flax) provided many arable weeds, welcome as these are usually scarce so early in the year. The company disbanded after hunting out the plants of Cottisford village, where we found rather few garden escapees, and I headed out alone to the last recorded location of Carex elata. I was quickly disappointed as this was an arable field, but diving into the woodland in the shallow valley below I immediately found around 20 tufts in a spring-fed swamp - as Carex elata had been known from only one site in the county this was clearly a significant find! I continued to find further plants, keeping count until I came across a large area of flooded woodland that supported thousands of individuals, and I was puzzled as to how this plant had been missed here for fifty years! Several large tussocks were also growing in Cottisford Pond itself.

Right: a tussock of Carex elata growing in Cottisford Pond. Below left: its wet woodland habitat. Below right: a diagnostic feature of C. elata is the leaf-sheaths, which split into many ladder-like fibres.

The woodland around Cottisford Pond had plenty of other good plants to add to the list, with a range of ancient woodland and wetland species. Neottia ovata (twayblade) and Valeriana dioica (marsh valerian) were both new to the tetrad, the latter a surprise as I had never known this uncommon and threatened species to ever turn up at a new site or to grow in woodland. To the south above the valley, the woods on the hill and the small area of Shelswell Park within the tetrad added a good deal of further interest. This area supported acid grassland, a very rare habitat in Oxfordshire, and I was able to re-record Campanula rotundifolia (harebell), Cirsium acaule (dwarf thistle) and Galium saxatile (heath bedstraw) as well as add Carex caryophyllea (spring sedge), Filipendula vulgaris (dropwort) and Veronica officinalis (heath speedwell) new to the tetrad. The glacial sand and gravel deposits across this part of the county, from Hardwick north-east to Finmere and Mixbury, would certainly be worth further survey.

After a bit more back-and-forth along footpaths to try to pick up extra species, I eventually returned to Cottisford carrying a satisfyingly full recording card. Together the meeting bumped the tetrad up to a total of 300 taxa, recording 260 taxa and making 287 records, greatly exceeding my expectations. It was particularly gratifying to find so many new native species and few aliens for a change, and of course to re-record a number of locally important plants. Who knows what we will find in a forthnight's time at the next meeting on May 6^th? Please email me if you'd like to join us.

Atlas recording 2018

This is a short post to advertise opportunities to get together with local botanists this season and help with the penultimate season of recording for Atlas 2020. I will be organising recording meetings every other weekend through the season under the aegis of the Oxfordshire Flora Group, with the first meeting on Sunday 22nd April in the north of the county in Cottisford. I am also going to be running an 'official' BSBI meeting on 16th June, but so far my organisation hasn't progressed beyond fixing a date and the vague locality of the Chiltern Commons. Get in touch with me if you would be interested in coming along to any of these. The Wychwood Flora Group will also be running recording meetings in the west of the county, mostly on weekdays. Email the group if you are interested in joining any of their outings.

The above recording meetings and more are all listed in the events calendar which you can view here.

As a teaser for the kinds of plants you might see while out on a recording meeting, this is a photograph of the nationally scarce Helleborus viridis (green hellebore) that Oli Pescott and I found growing in great plenty along part of Grimm's Ditch near Nuffield in the Chilterns while we were out recording today. It was a very special sight and we found many other nice woodland plants, including Viola reichenbachiana x riviniana (=V. x bavarica), only the third county record. Is it overlooked in Oxon? Keep an eye out for intermediate-looking violets this spring!

Atlas 2020 update

This post is just a short announcement and advertisement of the updates I have finalised to the Atlas 2020 page describing the project and progress with recording for the Atlas in Oxfordshire. I have over-hauled the previous interactive tetrad map, as you can see below. It includes a function to display areas in need of attention as well as the more usual illustration of well-recorded areas, and provides links to full lists of taxa recorded in each tetrad. I hope this will be of use to botanists planning recording this season.

The year in botany

Recording plants at Somerton during a field meeting in May 2017

Now that we're well into the new year I thought it about time I had a look back at 2017. Much more happened during 2017 than can be summarised here — you can get an idea of local activities during the last year by reading the blog posts. If you've any highlights you'd like to share then consider leaving a comment below this post. It was a memorable year for me, not least as it was my first full year in the post of vice county recorder. I have enjoyed beginning to get to know the county's flora and its botanists, particularly through meetings (ten of which were covered on the blog). Numerous local botanists have also been out enjoying themselves outside of meetings, and it has been a pleasure receiving their records and learning what they've been up to. It has been particularly gratifying to see new recorders find their feet (there was a beginner recorders' meeting in April), and for me to be in a position to assemble everyone's contribution to Atlas 2020.

So far 13,623 records made during 2017 have been submitted to the BSBI Distribution Database (DDb). A further 4,114 records were submitted to iRecord, but these have yet to migrate over to DDb. iRecord submissions were almost double that of last year due to new recorders taking up this platform, but 13,623 is a bit of a dip for the DDb compared with 2015 and 2016 when over 24,000 and 25,000 were submitted, respectively. If you have records please therefore send them to me! I blogged earlier in the year about the the vascular plant record sharing agreement with Thames Valley Environmental Record Centre (TVERC), which was quite a big development, making a huge difference to the BSBI's Oxon data holding, with over 340,000 records received. Many recorders over the last couple of decades have preferred to send their records to TVERC, and being able to tap this activity has made a significant contribution toward Atlas 2020. It has been and continues to be a big job to check all these records but it is worth the effort!

I'm sure you're desperate to read how the county is getting on with Atlas 2020 following the 2017 recording season — the up-to-date tetrad (2km square) progress is shown in the map to the left, based on DDb records from the beginning of 2000 to present. This shows more clearly than maps I've previously published how survey effort has been expended, with both tetrad total taxa (tetrad colour) and total recording rate (tetrad size) illustrated. While coverage of the county has continued to improve, one can see that there is work to do in terms of consolidating the recording done to date, i.e. increasing the cover of 'bigger squares' (generally a recording rate of 60% requires about 200 taxa to have been recorded), and recording in the far-flung areas around the county boundary. This is essentially the message I've communicated previously, such as on the Atlas 2020 page, so we just need to keep on working at this up to the conclusion of the Atlas recording period.

The Oxford and Otmoor areas (SP50 and SP51) exemplify the situation we would ideally like to reach but as I've said before it is not essential or possible to fill every gap. At the scale of hectads (10km square), which will be the mapped units in the published Atlas 2020, most now stand at 50-60% recording rate or better (and similarly for the re-find rate), and most have at least 20% of tetrads with 100 or more taxa recorded, which is quite a good situation; targeted recording during 2018 and 2019, including repeat visits to tetrads, will improve the recording rate. Please do get in touch if you need help identifying areas for recording in your area.

Tetrad coverage for Atlas 2020, with tetrads coloured by number of taxa recorded since 2000, and square size scaled by total recording rate, i.e. the proportion of taxa recorded since 2000 out of all taxa recorded.

Above: Potamogeton nodosus in the Thames, Frank Hunt. Right: Carex muricata subsp. muricata in the Chilterns, Geoff Toone.

Now I come onto the less dry developments of 2017, the records of notable plants. The record that stands out of course is Frank Hunt's rediscovery of Potamogeton nodosus (Loddon pondweed) in the Oxfordshire part of the River Thames, a nationally rare species which had only ever been known in the county for a short period during the 1940s. Its reappearance in the Thames it turned out had actually already been established on the Berks and Bucks reaches of the river by the Environment Agency a few years ago, but this was still a very exciting record for Oxon. This rediscovery follows that of Rosa agrestis (small-leaved sweet-briar) in the county in 2016 — I hope that we may have a rediscovery every year!

Recording meetings during the year turned up many records of note. Less satisfactory was the grotty umbellifer found growing submerged in the River Cherwell during the meeting in Somerton in May: it was suspected to be Oenanthe fluviatile (river water-dropwort), thought extinct in the county, but later searching could not relocate it and its identity remains a mystery. On the same meeting was re-found a small population of the uncommon crowd-pleaser Saxifraga granulata (meadow saxifrage), a larger population of which was also rediscovered in December at Peppard chuchyard on the New Year Plant Hunt. With the county generally quite under-recorded, there are plenty of opportunities such as these for re-finding notable plants at old localities as part of Atlas recording, e.g. Fay Banks' Sambucus ebulus (daneberry) at Garsington this last year. Recording also turns up unusual or casual plants, and this year I had an odd weekend when several records of the locally rare Anthriscus caucalis (bur chervil) were sent to me.

Finally, a little-known Oxfordshire plant, the nationally rare Carex muricata subsp. muricata (large-fruited prickly sedge), came to my attention this year when I received a batch of records from Geoff Toone and Paul Stanley from back in 2011. Only discovered in the county early in the 2000s (I think at Hartslock, though I can't find the record), this sedge is beginning to emerge as potentially quite a widespread plant of Chiltern beechwoods, and many thanks are due to Paul, Geoff and others for continuing to track it down.

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.

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.