Lockdown botany

Myosurus minimus found by Roger Heath-Brown in Garsington. Image by Roger Heath-Brown

I wonder what the ageing George Claridge Druce, great man of early twentieth century botany, did with himself during the Spanish Flu pandemic of 1918. Did he self-isolate at his home in north Oxford and work on The Adventive Flora of Tweeside (published 1919) or revisions to his Flora of Oxfordshire? Or did he potter about the town and along his local rivers, seeking the solace of wildflowers? I hope it was as sunny and floriferous for Druce and his contemporaries as it fortunately has been for us these last weeks.

I toyed with the idea of working on an (online) flora, but this seemed like too serious an enterprise for such a serious (and ridiculous) time. So, as I like to imagine Druce would have (in order not to make myself feel inadequate in comparison with his considerable industry), I have been exploring my local area more thoroughly than I have had time for in recent years. What have you been up to? I hope you have been able to get out and be cheered by spring wildflowers during your permitted exercise. A few botanists have been in touch with interesting things they've found this spring. I have had a few myself, and so I thought I'd write a blog post in an attempt to spread the cheer. Do leave a comment below if you have had a nice find you'd like to share.

Silybum marianum in a Wallingford alley. Image by Oli Pescott

First up, Roger Heath-Brown and Fay Banks separately emailed me about a new population of Myosurus minimus (mousetail) they'd both seen on their walks around Garsington. Originally found by Roger, plants were growing in a damp cattle-trodden field corner. This and similar places such as gateways are the typical habitat of this locally scarce species. Over the last few years I have also found a few new sites for this plant, all in gateways, mostly in the upper Ray, such as at Meadow Farm.

Oli Pescott tells me that on his explorations of the back alleys of Wallingford he has been finding a lot of Silybum marianum (milk thistle) and that it appears to be spreading. Over the river in the vice county of Oxfordshire, there certainly seems to be a trend also, with many recent records of a species that formerly was rather rare and casual in the county. Oli suggests that this Mediterranean native may benefit from climate change. If you'd like to see it, there is a large well-established population on the Dyke Hills at Dorchester. Do let me know if you find any elsewhere.


On her daily walk around Kidlington, Judy Webb found a plant not seen in Oxon for a long time, and only ever known from the Stonesfield area. This was the little grass Poa bulbosa (bulbous meadow-grass), which Judy found growing abundantly on a dry road verge, together with other coastal species such as Plantago coronopus (buck's-horn plantain). I wonder how it got here? With its fragile bulb-like stems, perhaps fragments were spread with mowers? It would be interesting to investigate if it is present elsewhere in the neighbourhood. I went to have look myself (on my way to do my grocery shopping) and found also a lot of Cerastium semidecandrum (little mouse-ear) growing with it, a locally uncommon or overlooked spring annual of short dry grassland (it turns brown and disappears after May).

Judy's colony of Poa bulbosa growing on a road verge in Kidlington. The plants are the yellowed patches around the edges of the verge in the left hand image. The bulbous bases are clearly visible in the image on the right. Images by Judy Webb.

Taraxacum berthae a new county record found by Judy Webb. Note the spotty leaves and adpressed outer involucral bracts. Image by Judy Webb

Like Judy and me, and other botanists stuck at home, you might have spent this period of lockdown looking at dandelions, the last few weeks being the perfect time of year for identifying these cheerful little plants. Judy's lockdown botany has continued to yield interesting plants, with her inspection of verges in Kidlington turning up a new county record, Taraxacum berthae (Bertha's dandelion). Judy shared her find of this unusual dandelion on Twitter and had it excitedly identified by keen taraxacologists Alex Prendergast and Josh Styles and confirmed by the BSBI referee. This is a rare dandelion of the north-west, so what it's doing in Oxon is a mystery. Was it introduced or could it be a relic of the old meadows that much of modern Kidlington is built on?

The fen dandelion T. palustre has for many years had a special allure for me, growing as it does in one of my favourite kinds of habitat (fenny meadows) but it has so far alluded me. Historically, there were four sites for this now endangered dandelion in Oxon, last seen in 1978. I have wanted for a number of years to look for it in the two sites that haven't been destroyed, Otmoor and Wendlebury Meads, both local to me, but I have always been too busy in April when dandelions are on show. Well, no problem with lack of time this year, and I found it surviving at both sites. It is difficult to estimate numbers since you can only really identify plants in flower and it is a small plant, but the populations seemed quite small, around a dozen flowers at Otmoor and half that at Wendlebury.

While looking for fen dandelion, I also found quite a lot of T. anglicum (English dandelion) in a different area of Otmoor, a new site, and at Wendlebury Meads growing with T. palustre, where it was last seen many decades ago. Nationally this is a much rarer dandelion but Oxford is a hotspot, with a number of sites in damp ancient meadows. My finds prompted Judy to send me a photo of a specimen she collected from Alvescot Meadows near Carterton which she thought was T. anglicum, and indeed it was (though I'm no expert). This is a significant westward extension of its Oxfordshire range.

If you are not convinced that dandelions are interesting, then I challenge you not to be impressed by the photos shown. Gorgeous little plants!

I wouldn't go as far as to say 'thank goodness for lockdown', but it's great to start the year with two county resurrections and a new county record. Fingers crossed for more good finds once this is over.

T. anglicum (top) and T. palustre (bottom) found at Wendlebury Meads. The narrow leaves and adpressed involucral bracts are characteristic of Section Palustria. The dark narrowly bordered bracts and deeply divided leaves of T. anglicum are diagnostic, the opposite situation obtaining in T. palustre with wide borders to the bracts and hardly divided leaves.

Great bryophytes at Great Tew

Despite Storm Ciara pummelling parts of Britain, no less than five bryologists turned out for our trip to part of the Great Tew estate (the valley at the bottom of SP3730). In the event, despite getting rather wet, the valley sheltered us from the worst of the wind, and the only slightly hairy moment was the explosive crack of a branch coming down further along the valley.

Although bryologists have visited the Great Tew area previously (e.g. Eustace Jones recorded Grimmia orbicularis on the estate, and mentions a record of Orthotrichum tenellum in a "wet wood in valley north of Great Tew"  in his 1953 paper on the mosses of Berkshire and Oxfordshire), very few localised records actually exist in the database of the British Bryological Society (older records tend only to have been entered as hectad summaries). This, then, was a great chance to explore a private woodland (we had permission!) and make some localised records for an area that is not well-represented in records databases.

After picking up various common pleurocarps after dropping into the valley, we also found Isothecium alopecurum on the roots of ash and fertile Cirriphyllum crassinervium nearby on soil. Soon after we found one of the things that we had been hoping for, a tufa-forming stream emerging out of the valley-side, as is often found in cuttings and valleys on the Oolite in the north of Oxfordshire. This particular one was not particularly blessed with bryological interest, although a large stand of Palustriella commutata featured in the centre of the stream, accompanied by Cratoneuron filicinum and Pellia endiviifolia.

Palustriella commutata clump in tufaceous spring

Soon after, an uncommon sight in Oxfordshire was seen, that of Plagiomnium undulatum fruiting. Jones (1953) listed this species as "sterile" in Oxon., and still considered the fact of its fruiting "rare or very rare" after forty more years bryologising in the county (Jones, 1991).

Plagiomnium undulatum in fruit at Great Tew.

By this point of the day we were rather sodden, and thoughts were turning towards home. Perhaps the nicest thing of the afternoon was a good population of the liverwort Plagiochila asplenioides growing along a track through the wood further up the valley side. Whilst this livewort is fairly frequent in ancient woods on heavy basic soils, it is not common in Oxfordshire overall, and is always nice to see.

Plagiochila asplenioides at Great Tew.

And finally, a nice photo of the epiphytic liverwort Metzgeria violacea that seemed extremely happy in the humid environment of this hidden valley.

Metzgeria violacea

Oh, and for the non-bryologists, we also saw Dryopteris dilata growing epiphytically in the crown of a fallen oak, which is not a habitat most Floras list!

Dryopteris dilata growing as an epiphyte on oak (foreground; background fern is Polypodium interjectum)

The full list of bryophytes seen in the valley at Great Tew is given below:

Amblystegium serpens var. serpens	Hypnum cupressiforme var. resupinatum	Zygodon conoideus var. conoideus
Brachythecium rivulare	Isothecium alopecuroides	Conocephalum conicum s.str.
Brachythecium rutabulum	Isothecium myosuroides	Frullania dilatata
Bryum capillare	Kindbergia praelonga	Lophocolea bidentata
Calliergonella cuspidata	Orthotrichum affine	Metzgeria consanguinea
Cirriphyllum crassinervium	Oxyrrhynchium hians	Metzgeria furcata
Cratoneuron filicinum	Oxyrrhynchium schleicheri	Metzgeria violacea
Cryphaea heteromalla	Palustriella commutata s.str.	Pellia endiviifolia
Didymodon sinuosus	Plagiomnium undulatum	Radula complanata
Fissidens gracilifolius	Plagiothecium nemorale	Atrichum undulatum
Fissidens incurvus	Rhynchostegium confertum	Cirriphyllum piliferum
Fissidens taxifolius var. taxifolius	Syntrichia virescens	Didymodon insulanus
Homalothecium sericeum	Thamnobryum alopecurum	Leskea polycarpa
Hygrohypnum luridum	Thuidium tamariscinum	Orthotrichum pulchellum
Hypnum cupressiforme var. cupressiforme	Ulota phyllantha	Orthotrichum stramineum
		Plagiochila asplenioides

Bryophytes of Dorchester (Oxfordshire)

Three bryologists met at Dorchester Abbey (SU5794) on a grey, drizzling morning for the fifth excursion of the season. The Abbey graveyard and buildings proved to have a lot to offer, with a grand total of 41 species, pipping our previous season's best churchyard at Bletchingdon (36 species). Probably the top find was Gyroweisia tenuis on the east facing walls of the Abbey. Gyroweisia can be easily confused with other species, particularly Leptobarbula berica, and the Sussex Bryological Group have an excellent blog on this topic.

Gyroweisia tenuis habitat (with Porella platyphylla in foreground)

The other nice find in the churchyard was Syntrichia papillosa. This is a species that appears to be spreading in lowland Britain, possibly helped by eutrophication of a range of substrates from various sources of nitrogen (e.g. NOx from car exhausts). On the other hand, it may be that the species is just recovering from losses during an earlier period of substrate acidification from SO2 pollution (and the loss of hedgerow elms). For example, Eustace Jones notes that Herbert Napier (recording in Oxon. 1909-1914) reported it as "not uncommon" and suggested that the species had increased since the time of Boswell (recording in Oxon. 1858-1897). Jones himself reported S. papillosa as "certainly rare" (this would have applied to the 1935-1953 period) and describes the species as typically only found in single locations within sites (and gives hedgerow trees, "usually elm", as the habitat). Perhaps at this point the species was still widespread but locally rare, meaning that it was often overlooked during surveys. Certainly it appears to have subsequently declined, as it was only recorded twice in Oxon. in the period 1953-1991 (Jones, 1991).

At Dorchester we found nice stands of the plant on a tombstone, but also on the slats of a park bench, suggesting a novel mode of gemmae movement! See the two pictures of the photogenic S. papillosa below:


The full list from Dorchester Abbey appears below:

Amblystegium serpens	Grimmia pulvinata	Rhynchostegium confertum
Barbula convoluta var. convoluta	Gyroweisia tenuis	Rhynchostegium murale
Barbula unguiculata	Homalothecium sericeum	Rhytidiadelphus squarrosus
Brachythecium rutabulum	Hypnum cupressiforme	Schistidium crassipilum
Bryum argenteum	Hypnum cupressiforme var. lacunosum	Syntrichia latifolia
Bryum capillare	Kindbergia praelonga	Syntrichia montana
Bryum rubens	Orthotrichum anomalum	Syntrichia papillosa
Calliergonella cuspidata	Orthotrichum cupulatum	Zygodon viridissimus var. viridissimus
Didymodon fallax	Orthotrichum diaphanum	Lophocolea bidentata
Didymodon insulanus	Oxyrrhynchium hians	Lunularia cruciata
Didymodon luridus	Phascum cuspidatum	Porella platyphylla
Didymodon nicholsonii	Plagiomnium rostratum
Didymodon sinuosus	Pseudocrossidium hornschuchianum
Didymodon vinealis	Pseudoscleropodium purum
Fissidens taxifolius var. taxifolius	Rhynchostegiella tenella

After lunch we walked a circuit through the Dyke Hills (SU5793) west of Dorchester, and then followed the Thames anti-clockwise back to the town.

The (flooded) Dyke Hills in winter.

The Dyke Hills are an Iron Age earthwork, and covered in a slightly improved form of calcareous grassland, the hills themselves presumably being formed from river gravels excavated locally. The bryophyte flora reflects this. After some time searching, we came up with the following, fairly meagre, list:

Weissia species	Homalothecium lutescens
Barbula unguiculata	Oxyrrhynchium hians
Brachythecium rutabulum	Phascum cuspidatum
Bryum rubens	Plagiomnium affine
Fissidens dubius	Pseudoscleropodium purum

The riverside circuit turned up several expected riverside bryophytes, including Syntrichia latifolia, Cinclidotus fontinaloides, and Dialytrichia mucronata, whilst the close inspection of a multi-stemmed willow in the floodplain of the River Thame at SU580937 yielded an impressive 15 epiphytes on one tree, including more S. latifolia and S. papillosa.

Chinnor Bryophytes

Our 4th bryophyte excursion of the 2019/20 season was to the old Chinnor Quarry at SP7500. Four bryologists were in attendance on what was a pretty grey and damp Sunday (12/01/2020). Despite this, things got off to a good start in the small, recently planted woodland adjacent to the car park at SP757004. Earlier in the year on a vascular plant survey this woodland had offered up some gems, including the White Helleborine (Cephalanthera damasonium), and it didn't disappoint now either. David quickly found Microbryum davallianum on crumbling soil along the central path through the woodland, alongside some infertile Aloina (most probably aloides judging by the amount of this species that we later saw in the old quarry).

Microbryum davallianum

Crossing over into the old quarry, now surrounded on one side by a housing estate, Aloina aloides (confirmed microscopically) was quickly picked up in the somewhat surreal damp chalky moonscape that dominates this area.

Aloina aloides

The Chinnor moonscape (ok, there was some grass as well...)

After inspecting what seemed like acres of Didymodon fallax, we picked up a few more unusual species, Campyliadelphus chrysophyllus for one. This is a species that is well-known to haunt the floors of damp chalk quarries, but it was the first time that any of us had seen it in Oxfordshire.

Campyliadelphus chrysophyllus at Chinnor

One species that we did hope to refind was Leiocolea badensis, a species recorded from the Chinnor quarries once in the 1960s, but never since. We found Leiocolea turbinata, its commoner congener, quite quickly, but, unfortunately, despite collecting several candidates for checking, we failed to locate the rarer species. Other interesting species in the quarry area included Campylium protensum, Cratoneuron filicinum, and Aneura pinguis, all in the vicinity of the large pond pictured below, and all species of damp calcareous habitats.

The pond area at SP759002

After lunch, we inspected an interesting area of sandy ground forming the football pitch of the housing estate previously mentioned. This was made of soil that had presumably been brought in for the purpose, and had abundant Phascum cuspidatum and occasional Pohlia annotina, the latter a species that has only four other records for Oxfordshire, and was last recorded for the vice-county in 1991. The rest of the excursion was filled by recording the wooded slope rising up to the Ridgeway footpath, and then circling back to the original car park. More Microbryum was encountered in patchy roadside grassland alongside the roundabout at SP758004, as was some Brachythecium mildeanum, our first record of this species for the season. The full list follows (duplicates are those recorded in the car park wood as well as the main square):

Mosses			Liverworts
Aloina aloides s.str.	Ctenidium molluscum	Orthotrichum affine	Aneura pinguis
Amblystegium serpens	Dicranella varia	Orthotrichum affine	Cololejeunea minutissima
Barbula convoluta var. convoluta	Dicranoweisia cirrata	Orthotrichum diaphanum	Leiocolea turbinata
Barbula unguiculata	Didymodon fallax	Orthotrichum diaphanum	Metzgeria furcata
Brachythecium mildeanum	Didymodon fallax	Oxyrrhynchium hians	Radula complanata
Brachythecium rutabulum	Didymodon insulanus	Oxyrrhynchium hians
Brachythecium rutabulum	Fissidens incurvus	Phascum cuspidatum
Bryoerythrophyllum recurvirostrum	Fissidens taxifolius	Plagiomnium undulatum
Bryum argenteum	Fissidens taxifolius	Plagiomnium undulatum
Bryum capillare	Funaria hygrometrica	Pohlia annotina
Bryum capillare	Funaria hygrometrica	Pseudocrossidium hornschuchianum
Bryum dichotomum	Grimmia pulvinata	Pseudoscleropodium purum
Bryum dichotomum	Grimmia pulvinata	Rhynchostegium confertum
Bryum pseudotriquetrum	Homalothecium lutescens	Rhytidiadelphus squarrosus
Bryum rubens	Homalothecium lutescens	Schistidium crassipilum
Calliergonella cuspidata	Homalothecium sericeum	Syntrichia laevipila
Calliergonella cuspidata	Hypnum cupressiforme var. cupressiforme	Syntrichia montana
Campyliadelphus chrysophyllus	Hypnum cupressiforme var. resupinatum	Syntrichia ruralis var. ruralis
Campylium protensum	Kindbergia praelonga	Thamnobryum alopecurum
Ceratodon purpureus	Kindbergia praelonga	Tortula muralis
Cirriphyllum piliferum	Leptodictyum riparium	Tortula muralis
Cratoneuron filicinum	Microbryum davallianum	Tortula subulata
Cryphaea heteromalla	Microbryum davallianum	Zygodon viridissimus var. viridissimus