A Swarm of Orchids

 Last week - when the weather was a bit drier - I went for  walk up the track from Tromie bridge  to Killiehuntly, just for the walk with no plans of botanising.  But I can't help looking...

To my surprise I found 2 fields on either side of the track with plentiful orchids, in flower, which seems quite late for this year. Not only were they plentiful, they were big and sturdy and on taking a closer look, I couldn't quite place them in a single species.  Because they were puzzling, I went back a day or so later and took photos and measurements of some important features.

First of all, I took a photo against a clipboard marked in 1cm squares, to give an idea of the scale. You can see that the biggest one in the photo is about 30cm tall.

I also squeezed the stem to check whether it was hollow or solid - you don't need to pick or cut the plant, as it is easy to tell if it gives a bit. (Spotted-orchids have solid stems and Marsh-orchids have hollow ones.)

The leaves were wide and unspotted (unsurprisingly, Spotted-orchids have skinny spotty leaves).

So far this seems to fit Northern Marsh-orchid (Dactylorhiza purpurella) though it is much bigger and flowering later than I would expect.  So let's check the flowers.  The shape of the flowers is really important in distinguishing between orchid species, especially the front lip of the flower.

A diamond shaped petal

This plant has a diamond shaped front petal (called the labellum)  which is characteristic of Northern Marsh-orchid - but it is the wrong colour. I would have expected it to be a dark beetrooty purple, whereas this lighter pink is typical of the Heath Spotted-orchid (Dactylorhiza maculata). Some of the flowers did have the petal shape of the Heath Spotted-orchid, with a little tooth in the centre:

A lobe (tooth) in the centre of the petal

but then it did not have the spotty leaves.

So I came to the conclusion that maybe it was a hybrid between the 2 species i.e. Dactylorhiza x formosa = dac. maculata x purpurella.  In order to check, I sent the details to the orchid referee Richard Bateman (the expert) at Kew and was delighted that he confirmed they were the hybrid. Richard is one of the many professional botanists who volunteer their time and expertise to check amateur observations.

I have never seen so many hybrids in one spot (there were well over 100). Although hybrids are known for their vigour, they are not always fertile.  It seems that this strain was and has produced many offspring in the same place (an orchid swarm). I was surprised that no-one had recorded orchids in this spot before, and I have sent off the records to go on the BSBI database.