A Paired Comparison of Pale and Magenta Forms of Green-winged Orchids

Two weeks ago my wife and I visited Eades Meadow in Worcestershire, which is a great place for Green-winged orchids.  They were just coming into flower, but it was noticeable that there were no pink or white plants, just the more normal magenta coloured plants.  Another member of a Facebook group dedicated to orchids to which I belong, visited a few days ago and found some white and salmon coloured plants.   It seems that they flower a little later than the magenta ones by a few days.

Do they differ in any other ways?  Are the pale ones bigger, or do they perhaps have more flowers.   To test this I went to Bernwood Meadows and later another BBOWT reserve, Pilch Field and made a simple paired study.  They are a bit closer than Eades Meadow.

Bernwood Meadows

Pilch Field

At Bernwood I estimated that the white and salmon pink forms were in a ratio of about 1:500 compared to magenta forms.  As a result there were only a few to be seen but of course they are very noticeable.  We paired up neighbouring plants. We selected a pale orchid and measured its height, number of flowers, the length of the spur and width of the labellum.  These measurements were then compared to those of the nearest magenta coloured plant. We ended up with 10 pairs at Bernwood, but only one at Pilch Field.   

Perhaps not surprisingly we found no differences between pale and magenta flowered plants; probably there is no difference but our sample size was small.  Intriguingly though the ratio of height to flowers for the pale plants was significantly different to that of the magenta form; the inflorescence was denser.  

The previous day I went to the private wood where I have permission to study a population of Greater butterfly orchids.  The day started well, with a group of hares in the arable field leading to the wood, )which I saw again on my way back to the car) and the orchids were in bud, though some were surprisingly spindly.   

In what has been designated the study area, last year there were 56 plants.  Their fate so far this year was as follows:

15 flowered last year - 9 in bud this year, 5 just in leaf, 1 no show

41 in leaf only last year - 10 in bud this year, 26 in leaf this year, 4 no show.

Greater Butterfly Orchid in Bud

Greater Butterfly Orchid in Bud

Bluebells

Hare - too fast for the camera(man)

I found and marked 30 new plants (one of which was in bud) were added giving a total of 81 plants showing either a bud or as a minimum a leaf.    A full count and measurement of height, leaf width, size of floral parts and number of flowers (if flowering) will be made in early June.   

Our Annual Orchid Count at Westwell Gorse

We went to Westwell Gorse, the BBOWT reserve south-west of Burford yesterday to repeat our count and measurements  this time last year of Early purple orchids   We have a  sample area which is unmarked but can be recognised by trees and bushes which we use as the boundary.  This year we counted 63 flowering spikes compared to 83 last year, due almost certainly to rabbits, the signs of which were very noticeable.  There were two or three chewed spikes on the ground.   On average the plants were shorter, (15.3 cm v 16.5cm, but the difference was not statistically significant.   The average number of flowers per spike was the same (9.8 both years).

 

We watched this sample area for 20 minutes just after noon in full sun.  During that period there were three insect interactions, one very brief.  One of the 63 plants was visited twice, surprisingly as it was only just breaking into flower.   The insects involved were all Rhingia campestris, not a known pollinator (The Flower of the European Orchid; Claessens and Kleynen), and indeed checking the plants involved, none of the pollinia had been removed.

The previous day I joined a recording group at Foxholes Wood, another BBOWT reserve, this time near Kingham.   As ever I found my patience and ID skills were well short of what was required, so I wandered off to see if I could find Herb Paris for which there are a few records.   I was not successful, and on rejoining the group they pointed me in the direction of some Early purple orchids which I had missed, growing in a damp shaded area by a stream, a complete contrast to the habitat at Westwell - grazed turf. 

      

Early purple and Green-winged Orchids: Not a hybrid in sight (Unsurprisingly)

Both Early purple orchid (Orchis mascula) and Green-winged orchid (Anacamptis morio) which are now in flower, are widespread and easy to find.  In the right spot there can be hundreds, even thousands.of plants.   Superficially they look rather similar, except that Early purples usually have spotted leaves, whereas Green-winged has unspotted leaves has but characteristic green veins on the two side sepals which form a hood.

They used to both be classified in the Orchis genus, but Green winged was split away, based on molecular evidence, and placed in the Anacamptis genus.   They both show significant, often attractive, colour variations from purple through to pink and white, but they do not seem to hybridise much with any other species.  There is though a hybrid between the two, Anacamptorchis morioides, which is an easily remembered name.   Unfortunately there are no records for this hybrid since the mid - 1970s on the BSBI database and only a handful before that, so what a challenge to find it and since there is less chance statistically of success than seeing the Ghost Orchid, Britain's rarest orchid (that at least appeared in 2009).

I started out by looking on the BSBI database for monads (1 km squares) where both orchids occurred in Oxfordshire and its surrounding counties, then looked at the individual records to see if they were close enough to be sympatric (ie grow close together).   I came up with 18 possible locations with the hotspot around Stroud in Gloucestershire (curiously also a hotspot for the Butterfly orchid hybrid).

Yesterday therefore I set off to that hotspot to share my day with golfers, dogwalkers (lots of them and the mess they leave - one woman had 9 dogs), horse riders and the odd off road cyclist, to look for the impossible, concentrating on orchids with spotted leaves and veined sepals.   Disappointingly the 1970s record is still the latest.

I started at Minchinhampton Common where both orchids grow quite close together, but only the Early purples were in flower. 

  

 I did find one orchid which I wondered about - unpotted leaves,spur a little less than 10mm and sepals gathered into a hood.  But there was no veining, so I concluded it was simply natural variation of a regular Early purple. 

                      

Then to Rodborough Common, a few miles north.   Here I could only find Early purples, though mixed up nicely with cowslips.

Though to the west, Selsey Common, proved more interesting.   Green-winged were more advanced and in places the two species grew very close together, the nearest being 20 cm apart. 

 But the numbers of both were small and there were no individuals with the slightest hint of hybrdisation.

 I spent quite a time watching a tachinid fly (I think, based on the wing pattern) thoroughly exploring a Green-winged orchid, waiting to see if it might, just might, detach a pollinia.  Sadly just as the moment approached, so did an uncontrolled, yappy dog which blundered into the orchid and the fly.   Harry was the dog's name I think, and imbecile that of the dog owner.