Sunday, 29 May 2016

Botany on the A34

Wednesday last week brought the fortnightly BSBI Workout (or Atlas 2020 Recording).   Sue had arranged permission for us to go over farmland between Enstone and Chieveley, 12 minutes drive from Hooky.   It turned out to be surprisingly varied and we notched up around 215 species (one every 75 seconds), with a riverbank, woodland edge, a real find, a species-rich limestone embankment, and at the end of the meander, a former, now overgrown, quarry.
Field Pansy on the Edge of  a Field of Oilseed Rape
Rough Comfrey (provisional - sent to referee)
I am by far the least able regarding botanical competence, and the party humours me by asking for my thoughts whenever an orchid in leaf is found, because I do have some experience with that family.(In fact we found two plants, which were probably Bee orchids (Ophrys apifera).   In passing, Sarah said she had found a large group of orchids on an embankment alongside the Newbury Bypass - the A34, which connects the M40 to the south coast, - but was not sure what they were and if I was passing the site she would appreciate a second opinion.

An invitation not to be missed, we went botanising on the A34 today, parking in a layby just beyond the orchids, ignoring the Wide Loads Only sign (and thereafter waiting for the police to show up to reprimand us or worse).   There must have been over 300 orchids on what anywhere else would be revered as species rich, unimproved,  limestone grassland.  
Newbury Bypass
 The most striking thing was the orchid colour, a deep, purplish magenta, deeper than the hue of most Southern Marsh Orchids (Dactylorhiza praetermissa) I have seen, but  to which I attributed most of the plants based on the labellum shape, unspotted leaves and so on.   Some plants though were hybrids known as D. x grandis with Common Spotted Orchids (D. fuchsii); this parent was only just coming in to flower.  The hybrid is fertile and can back cross with the parents, so some plants had mostly the characteristics of D.praetermissa but there was clearly introgression.   In fact the whole population might  be a little introgressed, given the deep colour, robust plants and the fact that they were flowering early.

D. x grandis

D. x grandis
D. fuchsii

Fortunately no one stopped to enquire as to what we were doing; whilst I busied,  photographing just about every plant, she did a survey of motorists and passengers on mobile phones to pass the time.  Maybe she will write her own blog.

At home I had the moth trap out on Friday night, with a catch of 16 moths, representing by 9 species together with 4 cockchafer beetles.

Pale Tussock

Tuesday, 24 May 2016

Cranham Common: Lesser Butterfly Orchids (Platanthera bifolia)

Cranham Common in Gloucestershire, a 40 minute drive from Hooky, has amongst other orchids such as Early Purple and common Spotted, records for both the UK species of butterfly orchids (Lesser: Platanthera bifolia, Greater: P. chlorantha).   

Cranham Common
Drinker Moth Caterpillar
Early Purple Orchid
We went there today to gather some data about the populations to compare and contrast with the dataset that we generated on Skye.  How does the morphology of plants compare growing 500 mile apart and in warmer drier conditions.    Our Skye results were summarised in a couple of notes we did for  BSBI News and in preparation, awaiting a little more work on the statistical analysis, we have a paper on plant longevity and climate influences. 

At Cranham we found no Greater butterfly orchids in flower, but in one spot perhaps 30 lesser butterfly orchids of which 10 were in flower.   Our Skye dataset says that lesser flowers earlier than greater, and maybe this was borne out at Cranham Common.    We measured height, leaf width, and the number of flowers for all 10, and the labellum width, length, spur length and width of flower for a few.

Lesser Butterfly Orchid
Lesser Butterfly Orchid
It is a little dangerous to draw with so few data points for Cranham but nevertheless the differences were not as large as I had expected, leaves quite a bit larger, 60%, and 39% more flowers, but the average height was only 18% greater at Cranham. 

N Lf width cm Ht cm Flowers
Skye >400  2.43 17.52   11.77
Cranham    10  3.82 20.75   16.33

The environment was quite different.   On Skye they seem to avoid competition but at Cranham in the open on a limestone bank, they were growing amongst grasses, roughly as high as the orchids.

Lesser Butterfly Orchid
I am hoping to get more data points from other localities in surrounding counties in the next few weeks (there are very few recent records for either species in Oxfordshire).

But the oddest thing was that of the 10, 5 were probably the hybrid P. x hybrida.  Whilst most characteristics such as the data above spoke to an identification as P. bifolia, the spur lengths were variable and the pollinia positioning was not parallel, and the subtended angle of the pollinia was greater than zero, but not as wide as P.chlorantha.   I have asked BSBI's orchid referee for his thoughts.   I think that the hybrid is more generally under recorded.

Putative Hybrid
Putative Hybrid
Putative Hybrid

Friday, 13 May 2016

Green-winged and Early Purple Orchid - Questions, questions.

It has been an orchid week; I seem to have spent almost every moment looking at Green-winged orchids (Anacamptis morio) and Early purple orchids (Orchis mascula), but ended up with a several questions about their ecology and more. 

Today at Leafield, I looked at around 150 GWO in 2 separate pastures, looking at the colour variation, and preparing to get data on fruit set efficiency.   I counted the number of flowers on the spike of roughly 40% of the population - average 5.7, std dev around 2.0. One group were on a steep bank, the other on a more gentle slope, but there was no statistical difference between average number of flowers of the two groups. I will go back in around 6 to 8 weeks to count developing seed pods; literature suggests that because GWO provides no reward to pollinators then seed set efficiency will be low.   (That's the first question).  In fact I found very few pollinia had been removed, though they only came into flower a few days ago, and the bursicle (i.e. pouch) surrounding the pollinia was quite tough and difficult to burst; I did manage to extract one pollinia using my pen, but it was a struggle.   (The second question: is there an opportune time for pollinators to visit, perhaps well into flowering?)

GWO - Pollinia partly detached, Leafield
GWO Pollinia
GWO Pollinia removed, Leafield
At Leafield I found just a single white GWO variant (0.7% of the total), and one pinkish plant.   Elsewhere I estimated 1% at Bernwood Meadow in Oxfordshire, and Wink's Meadow in Suffolk, but found none at Martin's Meadow in Suffolk.   Sampling is an issue because they seem to grow in clusters; my method was to follow a path and count all the orchids within 1 metre of the path to avoid bias towards cluters or otherwise.  As an aside why is everyone drawn to the white and pale variants?  (That's not a question for follow up, just an observation!)

GWO - White variant

I went to Martin's Meadow because it is unusual in having populations of both EPO and GWO intermingled (co-location might be expected to be more common because they have similar habitats - EPO possibly tolerates shade, and might favour edge of woodland more).  Orchids are often promiscuous (for example Monkey and Lady orchid hybridising at Hartslock in Oxfordshire)but in the case of EPO and GWO  there is only one record of a putative hybrid between them since 1970 in the UK, according to 'Hybrid Flora of the British Isles' (Stace et al) .  Despite being taxonomically close and with non-specific pollinators the pollen of one does not pollinate the other.  (Another question, why, but fortunately quite a lot of literature on the subject).   

GWO - Bernwood Meadow

GWO - Bernwood Meadow

Mixed Populations of EPO and GWO (one plant shown, foreground), Martin's Meadow

EPO - Sidlings Copse

EPO - Sidlings Copse

Unsurprisingly, I found no hybrids at Martin's Meadow, and the warden there, Paul, has never seen any either.   The closest I came was a very robust EPO plant (the largest on the reserve) with it's usual colouration and all the other EPO traits except that the leaves were unspotted. It had not GWO traits.   I did find out that it can be very wet in Suffolk, and that my boots ship water.

Finally I am laying claim to a new GWO variety - Janus, for obvious reasons.

GWO var. Janus (!)