Thursday, 10 May 2018

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


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.   

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