Thursday, 28 June 2012

Orchids and grasses (and a moth)

My local Spotted Orchids have started to flower - albeit a bit later than usual. The three main 'species' that I have locally are:

  • Common Spotted Orchid (CSO) - Dactylorhiza fuchsii
  • Heath Spotted Orchid (HSO) - Dactylorhiza maculata
  • Northern Marsh Orchid (NMO) - Dactylorhiza purpurella
These three freely hybridise with each other, and the hybrids back cross with the parents and with the other hybrids, so it is very rare to find a 'pure' or clean specimen anywhere: each specimen is likely to bear a component of each of the species in varying proportions. For that reason, the taxonomy of the two spotted orchids keeps changing, with them being variously described as species, subspecies or variants. But I just describe them all as hybrid spotted orchids. I recently had a long conversation with a leading orchid specialist, and when I asked him why we continue to try and name each specimen as A), B) or C), he said "it's just because we like to give different names to things that look different from each other, but really they're all hybrids".

I also have a suspicion that some of the variation is caused by the very local microclimate, for example if the orchid is standing in water or has dry feet. I generally find that specimens in water look more like HSO, but drier ones look more like CSO. The natural assumption is that HSO prefers water, and CSO does not, but if the water dries out for any reason, then the specimen that looked like HSO one year will look more like CSO the next year. I call these variations 'ecomorphs'.

Hybrid Spotted Orchid
That first one has features of CSO (the long tooth at the front lobe of the flower) and NMO (the overall colour is quite dark). The edges of the lip are slightly frilled, so there's some HSO in there, too.

And here's another:

Hybrid Spotted Orchid
That one has stronger frills and a paler colour, so I'd say 50/50 HSO and CSO.

These specimens were photographed at their best: the lower flowers have just opened and the higher flowers are still buds. When the flowers are all open, I think the plant looks less attractive.

I'll show more as I find them.

Grasses can be fun to identify, and the good news is that although the initial identification might be tricky, many species are readily identifiable in the field. One key feature is the 'ligule', which is formed where the leaf touches the stem:

Long, pointed ligule of Rough Meadow Grass - Poa trivialis

The long, pointed, ligule in the above specimen points us to Rough Meadow Grass - Poa trivialis.

Here's the grass:

Poa trivialis - Rough Meadow Grass
Crested Dogstail is easily identified by the one-sided nature of the seedhead (although I did manage to mis-identify it on another blog the other day):
Crested Dogstail
Cocksfoot is very recognisable:
While we're on Cocksfoot, I'll show this picture of one of the 'Minor' moths. There are three Minor species which are extremely difficult to separate, so unless we capture and kill them, we have to record them as 'Minor agg.':
Minor agg. moth
Minors use Cocksfoot grass as a food, living inside the stems when at the larval stage.

Yorkshire Fog must be the most common grass in this area: I find it in all but the wettest environments:

Yorkshire Fog
I just noticed the Rye-grass at the front left of the image.

The flowers of Meadowsweet have just opened and their perfume will dominate much of the hedgerow for the next couple of months:

Meadowsweet must be particularly nutritious: there are many species of insect and fungus which feed on all parts of the plant.

Now: hands up all those who ignored (or missed!) the Puccinia graminis rust on the Poa.

I was recently invited to talk about my blog by Nature Center Magazine. You can see the interview here. Thanks to Emma for that.

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