Sunday, 26 June 2011

Nearing 1400 species

The Spotted Orchids are now well advanced, with many specimens to be seen in the right places. The first is a good 'clean' Common Spotted Orchid:

Common Spotted Orchid
This second specimen - which was growing very nearby - has features of both Heath Spotted Orchid (the frilly lower lip, with only a hint of a central tooth) and also Northern Marsh Orchid (the dark background colour)
Hybrid Spotted Orchid
As I was examining the orchids, I spotted an Eristalis hoverfly attempting to nectar. I realised I had to work quickly, so I rattled off a few shots, and was rewarded with this fine shot of the hoverfly with the attached pollinia from the orchid:
Eristalis hoverfly with orchid pollinia
The hoverfly has a short tongue, which means it has to force its head deep into the flower to attempt to reach any nectar. Unfortunately for the hoverfly, the nectar is located down a deep tube, and can only be reached by insects with a long tongue, so the attempt is always futile. But the pollinia, which contain the orchid's pollen, are very sticky and attach themselves to the hoverfly's face, causing the hoverfly to withdraw and fly off. It then flies off to another orchid and pollination takes place. I have occasionally seen hoverflies sitting on other plants, trying to remove the pollinia. Score: Orchids 1, Hoverflies 0.

The Willow Leaf Beetle Lochmaea caprea is very common on its host plant where the larvae cause extensive damage to the underside of the leaves:

Willow Leaf Beetle - Lochmaea caprea

The Devil's Coach Horse beetle - Staphylina olens - is one of a large and difficult family of beetles - the Rove Beetles.
Devil's Coach Horse Beetle
All beetles have a pair of wings that fold up inside an outer, hardened pair: the elytra. In the Rove Beetles the elytra are extremely short and the wings are folded several times to fit under their hard casings. I have marked the elytra in the picture above, and it is clear that some severe folding is required to pull the large wings into such a tiny space.

To give some idea of scale, the Willow Leaf Beetle would comfortably fit between the antennae of the Rove Beetle.

The wet early summer has been great for fungal rusts. Pucciniastrum epilobii is a common rust on Willowherbs; in this case Rosebay Willowherb:

Willowherb Rust - Pucciniastrum epilobii
New to me.

It's worth mentioning here that fungal parasites are a good indicator of close relationships between species: Rosebay Willowherb looks quite different from other members of the Epilobium family, but has the same fungal parasite.


Emma Springfield said...

The hybrid spotted orchid is really pretty. It looks like some talented artist drew scrolling on the insides of the petals.

The Weaver of Grass said...

I read somewhere that Rosebay willowherb was once a favoured Victorian herbaceous border plant but that it became so rampany and escaped and so people began to devalue it. Shame really. I took a photo and intend to put it on my blog later today. I would grow it in my garden anyday but people would think I was mad!

Gill said...

Another fine page. Re the orchids, I agree with your ids, and would add the thickset flower spike and stout stalk also say "Marsh Orchid" to me.

That is a fantastic shot of the Eristalis with pollinia - I'm quite surprised the pollinia turn out to be green - I'd have expected them to be yellow somehow.

Stuart said...

Emma: the markings on orchid flowers are thought to resemble insects in order to act as lures for pollinators. I've certainly seen some convincing ones. Insects see in UV and infra-red, so they might be more convinced than we are.

Weaver: I certainly like it as a wildflower: it's very striking.

Gill: Yes. The pollinia are less yellow than I expected. They are a package of green sticky 'glue' and pollen grains, but the amount of pollen can afford to be relatively low since the huge losses expected from wind-dispersed pollen don't apply. It's more of a focussed approach rather than a shotgun. That might explain why they aren't so yellow (although pollen can be other colours, too). The only picture of Dactyl pollen that I could find shows that it's red.

Jim Endersby said...

I would love to include your photo of the Eristalis hoverfly with orchid pollinia in a book I am writing on Orchids. Please email me ( if you might be willing to allow this. thanks, Jim