Showing posts with label pollinia. Show all posts
Showing posts with label pollinia. Show all posts

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.

Friday, 26 June 2009

More on orchids

It has been suggested that really robust specimens like this one are showing 'hybrid vigour'. Since I consider them all to be hybrids, I rather think their environment might just have something to do with it instead.


The next sequence shows the gently graded colour variation from lilac to white:


That last one with no colouration whatsoever and yellow pollinia is known as Dactylorhiza fuchsii, ssp. o'kellyi, and is confined to western Ireland. No comment.


I raced to have a close look at these two when I saw them, and sure enough, the spike is short and the lower lobes are really frilly. A perfect Heath Spotted Orchid?

Not in my book...they just happened to be the only two with their feet submerged in the stream, and were less than a metre away from identically-coloured CSO with dry feet.

Still with orchids in mind, have a look at this shot of the hoverfly Helophilus pendulus:

Notice anything?

The hoverfly has some green objects stuck to its antennae. A much closer zoom in shows that they are, in fact, the pollinia of an orchid:

They must be quite irritating to the hoverfly, because it was quite clearly trying to remove them. Maybe hoverflies aren't perfectly built for this pollination task.