For the last 3 or 4 years we have been monitoring a patch of aproximately 20 vegetative seedlings in the main orchid colony. We presumed they were second-generation Lady orchid (Orchis purpurea) because they were growing close to our existing Lady orchids and appeared to be in a line leading back to one of the best plants.
This year (2006) we mapped them in as usual and were pleased to see that 10 had produced flower buds and were looking particularly lush and healthy. Something about the plants did worry me though because the flower buds seemed very purple and speckled, not the usual deep red colour of a Lady orchid.
Then to my surprise when the first flower opened, on a wet April morning, I saw it had the purple, curly legs of a Monkey orchid (Orchis simia), not the pink ‘crinoline dress’ of a Lady orchid (see pictures below). I immediately thought ‘hybrid’ for a number of reasons:
- the lip shape is like Monkey orchid but the legs are thicker
- the hood is strongly speckled (like Lady orchid) with a deep purple colour (like the lip colour of a Monkey orchid). The hood of both Monkey and Military (Orchis militaris) orchids is most often very pale (almost white) with streaks of purple scattered sparsely across the surface
- flowering period was 5 days after the Lady orchids and 1 week before the bulk of the Monkey orchids
- the hybrids are much larger and more vigorous than the normal Monkey orchid and much closer in form to the Lady orchid
- flowers open from the bottom up as in Lady orchid - not top down like the Monkey orchid
- foliage is lush and bushy, like the Lady orchid but is a grey-green, like the Monkey orchid
On discovering that we had potential hybrids I contacted BBOWT, the site owners, and we agreed to get expert advice before going public with anything. Also, the amount of damage caused by visitors to the slope (trampling of orchids and erosion) on a normal year is quite high so for the good of the site and the other plants we decided not to advertise the hybrids in any way this year. This doesn’t mean we have kept them secret - I tell anyone that asks - but we just don’t want to encourage hundreds of extra visitors in this the first year they have appeared.
Sadly, the slope around the hybrids has suffered very heavy erosion and damage this year - even with guide tapes to show people where not to walk; bright, white tags to show where the plants are and repeated requests for people to be very careful. Photographers have repeatedly trodden on small or vegetative Monkey, Lady and hybrid plants and in some cases all that is left is the broken white tags crushed into the bare soil.
I know that most visitors think they are being careful and would never knowingly damage plants but it still happens far too often. When people get excited they just concentrate on the flowers they have come to see and don’t notice how many plants they are treading on. Many even ask me what all the ‘other’ tags are for - the ones that don’t mark an orchid. But of course there are orchids on every tag position if you look closely - but 60% of the plants on the slope do not flower and are either seedlings or resting plants.
Scientific work
Very early on I took advice from a few trusted friends in the orchid world and Bill Temple (of the Hardy Orchid Society) suggested I contact Richard Bateman from the Natural History Museum, London (BMNH). He is one of the leading authorities on European terrestrial orchids and on hearing our news got in touch with Mike Fay from Kew Gardens and put together a team to visit the site.
Richard concentrated on pollen and morphological analysis, while Mike took samples from each plant to test the DNA. Pollen viability test will also let us know if there is any likelihood of the hybrids crossing back with either Lady or Monkey orchid and the DNA tests should confirm the parentage of these plants.
As you can imagine, there are several articles and papers in production, discussing various aspects of the hybrids.
Historical context
Orchid hybrids are not that uncommon in the wild, where closely related species grow together. However it is very rare to find a hybrid between 2 rare species of orchid and this might actually be the first natural hybrid between the 2 species recorded in the UK. However, in Europe the 2 species grow together more commonly and just a quick Google search for “Orchis simia x purpurea” will yield a few websites with photographs of French specimens.
A few years ago myself, Rod d’Ayala and Bill Havers started a project to contact the major national herbaria and record all the information we could about their specimens of UK Monkey and Military orchid. In doing so it became obvious that in the past Monkey, Military and Lady orchid were not only more common in the South Chilterns but may have actually grown together in a number of localities. Indeed, in the very earliest records collectors made no great distinction between the 3 species and there was great confusion about how many species there were.
In amongst the Military orchid sheets Bill Havers discovered a hybrid between 2 of these species but since his death I do not have access to his data so I can’t confirm which 2 species it was - but it was most probably Military x Lady. This winter I hope to revist the BMNH and Kew to check closely for hybrids. It is also interesting to speculate that perhaps some of the “Military” orchids might actually be hybrid Lady x Monkey.
Today we have just isolated colonies of these species and each one has gone through population collapses that have reduced the genetic variability massively. Monkey orchids on Hartslock were found to be very very closely related and we know from our herbarium specimen research that collectors seemed to favour the taller, more beautiful plants and these would have been removed and prevented from reproducing and passing on their genes. In the past the 3 species were never ‘common’ but they were much commoner and it is not a big stretch of the imagination to suggest that they must have had overlapping ranges as they have similar habitat requirements.
So, it is my theory that in the past the 3 species grew in colonies scattered all along the south Chilterns, with Monkey orchid favouring the western end, Military favouring the eastern end and Lady scattered amongst them. They probably hybridised much more frequently and the resulting plants were harder to split into 3 distinct species. Far from being a problem, these hybrids might actually be returning the population to a more natural state where occasional mixing of genes between the species was normal.
Should we be worried about the hybrids?
Many people have asked if we are worried about the appearance of hybrids and the potential for them to cross and recross with the Monkey orchids causing genetic pollution and over time wiping out the ‘pure’ Monkey orchids. They argue that not only would the Hartslock strain of Monkey orchid (smaller with pale flowers) not exist but whatever characteristics the plants have that enables them to survive on Hartslock might be lost and in successive generations a drought or cold snap might actually wipe out all the plants.
Personally, I don’t think we have enough information yet to know if this is a problem and we should probably just see how things go. This might be a one-off hybridisation and these plants might prove infertile and disappear in a few years. Also, if they do succeed and recross into the Monkey population the resulting injection of genes might actually do the population good. Remember, we know that they have gone through a very severe genetic bottleneck and from a genetic diversity viewpoint the plants are worryingly similar. Also, the plants we have on site now are very small when compared to some of the plants we have seen in herbarium collections and so even on the morphological side it is logical to assume that the colony should have much greater variability.
