Ptyxis Ecology - Our Botany Blog

Saturday, 17 January 2009

Fragrant orchids

Ok, I know I said before (see 'Orchid overdose' - July2007) that I might never blog about orchids again, but I did just say 'might'. I suppose I now have to admit that I've become an orchid fancier (almost). I've been surveying upland hay meadows in the North Pennines for the last 3 years and although orhcids are quite uncommon in hay meadows now, I have seen some of them often enough to start to get interested. I had a lot to learn about British orchids and I found Michael Foley and Sidney Clarke's book very useful. I didn't know the fragrant orchids at all when I started but have now seen all three types.

Up to a few years ago most people were happy to call them all 'fragrant orchid'. Frances Rose (who must be a leading candidate for being Britain's most outstanding field naturalist) divided them into three types a long time ago. His view has now been backed up by DNA analysis. They are likely to appear as separate species (or sub-species) in the next edition of Stace and it will be interesting to see what kind of patterns emerge in geohgraphical distribtution and habitat preferences of the three types, as more people start to record and map them. If you look at the distribution maps on the BSBI website you will see how under-recorded the sub-species are currently compared to the species.

This is Gymnadenia conopsea borealis (or just G. borealis if you prefer), which I have found in eight different meadows. It seems to be easily the most common of the three around here. In the hay meadows it is normally now confined to unmown (and unfertilised) banks, often growing in quite acidic U4c vegetation with species like betony and bitter-vetch. The lower lip of the flower (labellum) is almost not lobed at all and is longer than wide. The two lateral sepals are not exactly horizontal, but point a bit downwards.

I've found this one, Gymnadenia conopsea conopsea three times, but only a very small number of individuals in each case. (Sorry about the rubbish photo!). It is supposed to prefer more calcareous conditions. The labellum is much more lobed than borealis with the 3 lobes being about equal in size. Overall the labellum is about as long as wide. The lateral sepals are wider than borealis but still point slightly downwards.

This one is (I think) Gymnadenia conopsea densiflora, which I've only found once. It is supposed to prefer damper grasslands than the other two. It is also lobed and the middle lobe is supposed to be smaller than the two lateral lobes - although that isn't very obvious on this specimen. Overall the labellum is wider than long. The lateral sepals are wide like conposea but this time they do point out exactly horizontally. I found quite a big population of this growing on the edge of a meadow right on the riverbank of the Tees near Cronkley Bridge. The three types are supposed to have a slightly different smell, but I haven't sniffed them enough to know if that works for me yet.

Sound easy doesn't it. Well it's not! I thought it was fairly easy until I found the densiflora population. Both conopsea and borealis were there also, but the most common Gymnadenia there appeared to be intermnediate between densiflora and conopsea. Presumably these are hybrids. The three types are probably quite closely related, so its not surprising that if they grow together they would hybridise. Even if they have fairly strict habitat preferences, it is often possible to get a mixture of quite different soil conditions within a very small space, so not that unlikley to get them together at least sometimes.

They are nice plants. Its good fun trying to figure out a new botanical puzzle. But the main reason I like them is because they always grow in nice habitats.


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