Sunday, 1 February 2015

Brrr... A cold walk into Daventry

I arose this morning and threw open the curtains to bright sunshine. There were several jobs to do in Daventry so, after the usual early morning preliminaries, I set off. The sun was telling porkies; it was very cold, a strong northerly wind creating a significant chill factor.

A holly bush on Badby Road West bore a leaf with an odd mine. There is, according to the literature, only one leaf miner on holly, the extremely common fly Phytomyza ilicis. This has received numerous mentions on my blogs but this example seemed different.

The mine consisted of only a translucent 'window' of tissue. The original occupant had long gone but, when occupied, the mine must have been blister-like. A trawl of the internet failed to come up with anything similar.
Holly Blue(?) damage on a holly leaf.  Badby Road West,
Daventry. 1 February, 2015

I began to have my doubts. The photograph clearly shows a hole in the leaf above the 'mine'. It is evident that something had been feeding on the leaf without forming a true mine at all.

The obvious other possibility is that it was the work of the Holly Blue, Celastrina argiolus. The larvae of this butterfly will feed on the young, tender leaves and presumably if the leaf continues to grow and mature these patches are the result. My conclusion is that Holly Blue was indeed the culprit but confirmatory photographs of the leaf damage seem not to be available on the internet.

A little further on gorse was, as usual, in flower at the roadside. With weather conditions being such that brass monkeys ventured out at their peril, it was clear that these flowers had no chance of an insect visitor.

Gorse pods developing. Badby Road West, Daventy.
1 February, 2015

And yet, fruits were clearly forming. As gorse is a member of the Pea Family, Fabaceae, the fruit is a pod which, in warm, dry conditions, will split open explosively to fling the seeds for a considerable distance.

Research has shown that in spring 75% of the flowers on gorse are successfully pollinated. In the winter this figure drops to 43% but, by my reckoning, that isn't a bad result. It would suggest that gorse has a successful system of self-pollination or that fruit development following pollination by insects in the autumn is somehow delayed.

But why flower in winter at all? One possibility is that the flowers escape being eaten by caterpillars or browsing animals, although I find this argument unconvincing with regard to browsing. As gorse is a seriously invasive plant in some parts of the world quite a lot of research is going on regarding its seed production.

Speaking of winter pollination, my walk into town continued and I passed a fine alder tree, its catkins all a-dangle. These will of necessity produce a vast amount of pollen, each grain only having the tiniest chance of encountering the stigma of a female flower.

Alder catkins near Brook Street, Daventry.
1 February, 2015

We may be astonished by this profligacy and yet it works. But the effectiveness of this pollination strategy is of scant consolation to those who are allergic to the pollen, which has, I learn, 'a moderate to high level of allergenicity'. Now you know.

I have refrained from giving this alder specimen a Latin name as, although it is probably our native Alnus glutinosa, the Grey Alder, Alnus incana*, from southern Europe, is widely grown. With no leaves to guide me, I can't be sure, but one thing was certain, I wasn't going to hang about looking for evidence!

I scurried on into town, glad to take refuge in a coffee shop where I had arranged to meet my wife and daughter.

Finally, a puzzle. My blog site doesn't aim to appeal to a wide audience and I generally only get about 30 'hits' a day. Suddenly, on 29 January, it shot up to 93 before settling down to normal. I wonder what sparked all this activity?

* Latin incana - grey, hoary

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