Monday 18 June 2012

Gap in the clouds

An unexpected gap in the clouds prompted me to visit our highest local point in search of orchids.

Northern Marsh Orchid is the first of our local Dactylorhiza orchids to open:

Northern Marsh Orchid
All of the Dactylorhiza orchids freely hybridise with each other in a fertile manner, so I always like to assign a percentage of the three local 'species' which appear in any specimen. The first specimen, above, is very close to the 'clean' specification, (short spike, dark flowers, clean edge to lip of flower) so it is mostly Northern Marsh orchid.

The next specimen is paler and has a slight tooth to the front edge of the lip, so I'll give it 90% Marsh and 10% Common:

Northern Marsh Orchid with signs of Common Spotted Orchid

This third specimen is clearly a hybrid with Common Spotted Orchid (tall spike, still paler flowers, visibly sharp tooth):

Northern Marsh Orchid x Common Spotted Orchid

I'm pretty sure that third one has some Heath Spotted Orchid in it too.

Interestingly enough, the hybrids tend to follow the flowering dates of their major partner: Northern Marsh Orchid is always around 3 weeks earlier than Common Spotted or Heath Spotted, with hybrids somewhere in between, so it's not only physical characteristics that are shared. My 'clean' Spotted orchids are only starting to make spikes now.

I was astonished to also find a Common Twayblade orchid in this location:

Common Twayblade

I strongly associate Common Twayblade with limestone, so the road in this area must have been fortified or built with limestone chips, since this location is in a strongly acidic heath area. We need to be alert to just how much our actions can affect populations of plants (and hence insects).

Staying with the theme of habitat alteration, this part of the heath has become overrun with False Salmonberry:

False Salmonberry

False Salmonberry is an american rubus species that was introduced in Northern Ireland to support game birds for shooting. I first saw it locally about 5 or 6 years ago as isolated specimens, but now it has covered acres of heath, eliminating native species as it spreads. It is clear that this is yet another highly mobile and invasive plant.

Bumblebees that are brighter than usual tend to be males, especially if they have yellow hair where black would be expected.

Male Bombus lucorum
The tuft of yellow hair on its 'nose' is a clear indicator, but the overall colouring (in association with the absence of pollen bags from the hind legs) leaves little doubt. The flower is Common Catsear.

The hoverfly Sericomyia silentis is an excellent wasp mimic:

Sericomyia silentis hoverfly
It's quite a common hoverfly, but I rarely see it in large numbers.

2 comments:

Gill said...

<> I'd agree with the first part of that statement, but this year at least I have seen "heath" spotted already fully out (as is northern marsh) - and heath/common hybrids are half out. Ho hum.

That's a superb shot of twayblade - and I'd certainly agree with the suggestion of limestone chippings as the lime source.

<> Oh dear.... the more I hear about game birds and their effect on the landscape, direct or indirect, the crosser I get! Round here pheasants have completely destroyed the ground flora in many of our woods, including once-fine ancient woodland.

<< It's quite a common hoverfly, but I rarely see it in large numbers.>> Same here - bet you can hear it though :-)

Gill said...

Sorry - the blogger stripped out the quotes, which were:
"the hybrids tend to follow the flowering dates of their major partner: Northern Marsh Orchid is always around 3 weeks earlier than Common Spotted or Heath Spotted" and "... introduced in Northern Ireland to support game birds" respectively.