Monday, 5 August 2019

Rare Arable Weeds

Taking a break from searching for helleborines which has been my focus for the last 3 weeks, on Saturday I joined the Wychwood Flora Group's annual survey for Red Hemp-nettle (Galeopsis angustifolia).  It's rare, described as nationally critically endangered.  There is one consistent location a few miles south of Chipping Norton in the headland of field near Lidstone, which because of the farmer's interest, never gets sprayed.  The vast majority of the Oxfordshire records are from there.

Growing up in the Lake District where farmland is either pasture or was at one time hay meadows, I had never seen arable weeds until I moved south, so they are a bit of a novelty for me.   On Saturday there were probably more plants there than had been seen for a long time - robust, branched, growing up to 30 cm.   Stunning, and not difficult to find.
Red Hemp-nettle

Red Hemp-nettle

Red Hemp-nettle

There were other interesting plants such as  night-flowering catchfly (Silene noctiflora), - scarce in Oxfordshire - and because we started out quite early, the petals were flat and white (arguably a very pale pink), rather than curled over to reveal the creamy underside, causing much confusion, mainly initiated by me because in a field at Coldharbour a couple of weeks ago I saw plants just as they should be so at Lidstone I was rather dogmatic about curled over creamy petals!.   Other nice things included round-leaved fluellen (Kickxia spuria) and dwarf spurge (Euphorbia exigua).

Night-flowering catchfly

Night-flowering catchfly

Night-flowering catchfly, Coldharbour Farm in the afternoon

Round-leaved Fluellen, Coldharbour Farm
My Hill's Herbal, 1812, gives an alternative name for the fluellen as Elatine and notes that the juice is cooling and astringent, though collecting a usable quantity from this little weed would seem to be quite a challenge.

Tuesday, 25 June 2019

Meadow clary (Salvia pratensis)

A quiet weekend near home after a trip north last week to join a  Skye Botany Group walk over the limestone pavement at Torrin where the highlight for me was dark red helleborine in leaf (others found the sedges more exciting!), and  Aviemore for coralroot orchid among other nice things, 

Heath Fragrant Orchid at Torrin
Small White Orchid, North Skye

Coralroot Orchid, Aviemore

Coralroot Orchid, Aviemore
Meadow clary is a nationally scarce native which has a stronghold in North Oxfordshire, particularly an area around Charlbury on the oolitic limestone.  Quoting from 'Threatened Plants of Oxfordshire' it prefers waysides and ancient grasslands on chalk and limestone, with perhaps raised magnesium levels.  Seed generates readily but not in close sward.

Described as nationally near scarce, in Oxfordshire it is not so, if you know where to look.   For many years the Wychwood Flora Group (originally the Cotswold Rare Plant group) has been monitoring most of the populations and undertakes an annual census.   I joined the survey of three sites on Saturday; it proved to be very worthwhile, not only to see the meadow clary because in addition we came across a wasp orchid (Ophrys apifera var. trollii) on a road verge near Crawley.   On the same verge was a single plant of cornflower, now a rare arable weed, growing on ground disturbed by cable laying, and almost certainly not introduced, together with long-stalked crane's-bill, both of which are covered in 'Threatened Plants of Oxfordshire.

Wasp Orchid
Wasp Orchid

Long-stalked Crane's-bill 
Pyramidal orchid var. albiflora

Pyramidal orchids

We found lots of pyramidal orchids, including a couple of pure white plants (var. albiflora) some normal bee orchids and inevitably common spotted orchids.

Yet the best is still to come.  On Thursday evening another location will be visited - near Fawler - which has thousands of meadow clary plants including white forms, and is probably the best site in the UK.  Even better there is a good pub not far away too for later.

Saturday, 8 June 2019

Annual greater butterfly orchid counts in the Chilterns

A busy week.   I made a counts of greater butterfly orchids in 3 Chilterns locations.   At Greenfield farm there are around 500 plants, with 196 flowering spikes last year.  The plants are in two enclosures, fenced to keep out deer.   Plants are spreading outwards beyond the fences.   This year, the third, I counted all the plants, flowering and non-flowering, in the South enclosure but because the sward - dog's mercury, cleavers and nettles - was so dense in one area, I only counted flowering spikes in the other, North, enclosure.   And it rained. 

Both enclosures are shaded by young beech and ash, but because the ash has succumbed to die-back, light levels are increasing.   During the winter bramble was cut back and then in March I used a brush cutter to limit the dog's mercury in the North enclosure, though I don't seem to have made much impression on it. The heavy sward is choking out the orchids there.  

Sub-section with all plants marked

Almost ghostly in the early evening
A statuesque  greater butterfly orchid

The number of flowering spikes was dramatically less than last year; there were only 65 compared to 196 last year.

Snails were a significant problem in early April, so that this week plants that had been damaged then looked very unhappy, and the effect will probably be seen next year also because tuber growth will be impaired because of the leaf damage.  In one sub-section where I made detailed measurements of all the plants over a third of the plants had serious leaf damage, and the number of plants 'lost' i.e. nothing showing, was roughly a third of the total plants there last year, a rate of attrition far higher than we have seen in the last 2 years.

Leaf damage by snails

The enemy.
Winter was mild; and I wonder if this has led to a big increase in the number of snails.

Another possible cause of the fall in numbers might be climate.   The early autumn last year was very dry.   Could this have constrained tuber development and the ability of plants to flower?   Lots
of analysis to do in dark winter nights!

I made a count of the flowering spikes at Bald Hill, part of the Aston Rowant NNR.   A simple traverse but the same as last year, gave me a total of 18 flowering spikes, compared to 26 last year.  Unlike Greenfield these are plants out in the open, and although the reduction in numbers in percentage terms was not as great, it was noticeable that the plants were small.  One blessing was that it did not rain.

The third count of the week was of the butterfly orchids at Warburg NNR, the BBOWT reserve.   There it really did rain, so much so that my pocket voice recorder got damp and gave up on me and my waterproof clothing proved to be anything but.   I have yet to complete the analysis of the count but numbers there were also down on last year.   For instance I could find only 1 flowering lesser butterfly orchid (4 last year)  and I could find no greter butterflies on one of the rides where there had been several last year.

Lesser butterfly orchid

I did though find 3 bee orchids (in the rain inevitably).

Bee orchid

Saturday, 4 May 2019

Looking for an intergeneric hybrid more in hope than expectation

I still have not given up on the search for the putative intergeneric orchid hybrid - the cross between Green-winged orchid (Anacamptis morio) and Early purple orchid (Orchis mascula).  I am very doubtful, as is much of the literature, about whether it exists in the wild in Britain though there are a few, old, records on the BSBI database, the most recent from 1985 from Arnside made by a reliable recorder, and recently I saw a picture of this plant. Even so, I am not sure if I was convinced.   

Both are pollinated by bees, including bumblebees, but both show low rates of pollination success (20 to 30% seed set for Green-winged and around 10% seed set for Early purple), not surprising perhaps given that they flower early.   In addition there are possibly reproductive barriers to cross fertilisation.

Last Sunday I went to Minchinhampton Common and then to Selsley Common in Gloucestershire where both are intermingled looking for plants that ideally had spotted leaves (characteristic of early purple, though not always) and veining on the sepals (characteristic of Green-winged) even if just a hint.   I found nothing, and so to another site yesterday near Snowshill, around 20 miles from Hooky, to what looked like an old quarrying area.   The same story, despite looking at perhaps more than a hundred plants - at least - where both parents were close together, dwelling on a handful, but concluding that they they fell on one side of the fence or the other.  

Early Purple Orchids

Early Purple Orchids

Green-winged Orchid

Green-winged Orchid

A few colour variations of both were interesting but the highlight undoubtedly was the twenty or so plants of Pasqueflower (Pulsatilla vulgaris) and lots of Meadow saxifrage (Saxifraga granulata).

Pasque Flower

Pasque Flower

Meadow Saxifrage

Meadow Saxifrage

Sunday, 14 April 2019

Hook Norton's Grape Hyacinths

I took part in the annual count of Muscari neglectum in and around Chadlington by the Wychwood Flora group on Friday   I have not seen the final count yet but my impression was that it was a 'good' year for flowering plants.   Muscari neglectum is the recognised native species of Grape hyacinth, with its distinguishing dark navy to violet black flowers beneath a few sterile blue flowers at the top of the spike,  compared to the royal blue of the garden plant, Muscari armeniacum, an introduction from south eastern Europe.

Muscari neglectum held up against a group of M. armeniacum 

Druce's Flora of Oxfordshire gave several locations for Muscari neglectum in the early 20th century but now I think it is restricted to Chadington.   It is nationally rare.  

Well it also occurs in Hook Norton, and I spotted the plant in a display at the village garden society annual show yesterday (which won first prize in its class).  I went to the garden from which it came and then continued round the village, finding the plant in several gardens and overflowing into verges, not unlike Chadlington.   They are not cultivated in any of the gardens, they are just there, sometimes profusely in amongst grass.   

There are four hotspots in the village, the common thread being that all are in gardens which have been around for at least 100 years - The Bourne and Bourne Lane especially where the houses back on to what used to be allotments, the East End, Park Hill and near the Brewery, where there are also what look like plants intermediate between the two species.  The only question is therefore  whether it was introduced into gardens or occurred in surrounding farmland in the 19th / early 20th century, and crept in as a weed.  I rather fancy we will never know.

Near the Brewery

Park Hill

Tuesday, 9 April 2019

Snails and butterfly orchids at Greenfield

I went to Greenfield in the Chilterns yesterday.  The greater butterfly orchids are now emerging and recognisable, but they have suffered significantly from snail attack over the last month.   In some cases the entire growing tip has been eaten off.

The effect of snail damage can be summarised as follows. There were 92 numbered plants in what we term the study section last year, and I added a further 4 yesterday, bringing the total up to 96.  Of these:

Nothing above ground     28  (maybe at least partly due to snails)
Chewed but plant visible  15

Recognisable leaves        53
 of which 3 leaves             2
              2 leaves           29
              1 leaf               22


Of those with recognisable leaves 24 out of the 53 had suffered some snail damage.    The landowner put slug pellets down after my visit to try to curtail further damage.   This is one of the snails found in the laef litter

The snail damage has been much more severe than last year, probably because the spring has been mild and reasonably damp, whereas last year March and April were colder than normal, but then I do not know much about snail ecology, which for anyone studying orchid populations seems increasingly important.

In the north enclosure, where there were 258 plants last year including juveniles, I put bamboo stakes by the emerging plants, and removed by hand as much of the Dog's mercury as possible around the emerging plants so they do not get overwhelmed as happened last year.   I did not make a count but there were around 150 stakes.  Because only a few of the plants are numbered it will be impossible to pick up on losses from snails but I am sure the worst impact is in the south where the leaf litter is deeper, because there are two large beech trees overhanging the area.    

On a slightly better note, the orchids are spreading beyond the two enclosures, and I counted 40 plants in an area over which I put the brush cutter a month ago.

Next year we might consider taking off some of the leaf litter, but it may be beneficial to the germination and development of new plants.   I don't know!

Saturday, 6 April 2019

Plants around Epwell using the iRecord App

Despite being a member of BSBI since the early 1990s when you almost had to get someone to give you a reference before you could join,  I have made a minimal contribution to the Society's Atlas 2020 recording programme, where minimal equals zero.   Atlas 2020 is a follow up to plant distribution atlases in Britain and Ireland, first prepared in the 1960s and again in 2000.  The north of the county is under-recorded because of a lack of botanists, and frankly because it is actually quite dull.

I am only half a botanist; I can recognise a fair number of plants but know only a few of the scientific names.  Presented with a recording sheet where all the names are abbreviated Latin names is just not something I can cope with.   However the iRecord App makes life much simpler.  Plant lists are easy to create either by inputting common names or the scientific names and of course it automatically stores location data.   I tried it out yesterday on a walk from Sibford Gower to Epwell, two villages to the north of Hook Norton, sticking to paths across fields plus a wander around Epwell.

Ditchedge Lane
 I came up with just under 60 plant species, none of which were noteworthy.   But the App proved effective.  The only downsides were that it was heavy on the phone battery, and I was not able to download my list of plants before I submitted the records to the central database.  Once submitted  a list could then be extracted.

Field Pansy (Viola arvense)

Ivy-leaved Speedwell (Veronica hederifolia)
 Probably the nicest find though was this micromoth, which I think is Agonopterix heracliana.

Agonopterix heracliana