Wednesday, 21 June 2017

Alder - but no wiser

Earlier today I walked through what was once Stefen Leys Pocket Park. It is now just an open space owned by the local authority but is still a pocket park in all but name.
It boasts a small pond which, lacking proper management, has become overgrown by Yellow Flag, Iris pseudacorus, so that, from a distance,the pond can barely be seen. Normally, in spring, this pond is full of frog spawn but what happened this year I have no idea as I failed to pay it a visit.
The pond at Stefen Leys 'pocket park'. 20 June, 2017

The irises are attractive but the most interesting feature at the pond margins is an Alder, Alnus glutinosa. A quick glance shows nothing of interest but I, thirsting for spiritual enlightenment, took a closer look. The obovate leaves, for the most part, were normal, but some had been galled by a mite, Aceria nalepai. The galls, always situated in the angles of the leaf veins, are very distinctive and the mite is a widespread one.
Alder leaf galled by the mite, Aceria nalepai.
Stefen Leys Pocket Park, 20 June, 2017
Even more interesting however were the female catkins. These are not the usual lamb's tail shape of, say, a male hazel catkin, but are short and barrel-shaped. Something in the order of 10% had been attacked by a fungus, Taphrina alni, known as Alder Tongue. The name is very appropriate for the fungal body protrudes from the catkin in a distinctly insolent manner. The example photographed has a pinkish hue but this may darken to a red or even purple over the next few weeks.
Female alder 'cones' galled by Alder Tongue. Stefen Leys Pocket Park,
Daventry. 20 June, 2017
Once very rare and confined to Cornwall it has, in the last sixty years, spread across much of Britain. A little later in the day I examined a grey Alder, Alnus incana, and it showed no sign of the fungus.
What else did the park have to offer? Half a dozen Shaggy Parasol mushrooms, Chlorophyllum rhacodes, grew in the grass. 'Edible and delicious' is Paul Sterry's view in his Fungi of Britain and Northern Europe' but Roger Phillips' view - Mushrooms  and other fungi of Great Britain and Europe - is 'Edible, but may cause gastric upsets' Needless to say, I gave it a miss.
Shaggy Parasol mushrooms are very common.  Stefen Leys Pocket Park.
20 June, 2017
And then there was the bee in the trumpet flower of Hedge Bindweed, Calystegia sepium. Except, of  course, that it wasn't a bee at all but a Narcissus Fly, Merodon equestris. Unlike a bee it has two wings rather than four. The eyes are separated by a small gap and show that the specimen is a female. The fly is obviously a bee-mimic but comes in several colour variations, so it can in effect mimic several bee species. The one I photographed is var. validus.

A hoverfly, Merodon equestris. Stefen Leys. 20 June, 2017

So, as I say, the area is no longer a pocket park but, despite the little dumps left by dogs (to be fair, these dumps are getting less common), there is much of interest to be seen there. Perhaps I should pay it a little more attention.

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