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.

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

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!

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.

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).

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.