And so it begins …
This is part one of the story of Oak galls – there will be a sequel (possibly two) because the poor old oak tree, one of the most iconic of British trees, the one almost everyone can identify, is also one of the trees most attacked by galls (though, in this case, the galls do little, if any, damage to the actual tree). This first Oak attack story is a bit like the chicken and the egg – which came first? – as Neuroterus quercusbaccarum, a wasp so tiny that only expert spotters ever actually see it, has the ability to reproduce both sexually and asexually, producing two types of gall on oak trees: the sexual generation is produced inside the Currant galls and the asexual generation develops inside the Common spangle galls.
Let’s start with the Currants. As their name suggests, they look a little like currants or berries, maturing in colour from yellow and green to red and purple. In spring, you can find these attached to an Oak’s catkins or to the undersides of leaves.
Inside, tiny larvae develop, emerging as adult wasps in June. These wasps are either male or female, they mate soon after emerging, then lay their eggs within the epidermis on the undersides of oak leaves.
Now to the Spangles. When the eggs of the Currant gall generation hatch and their larvae begin to develop within the oak leaves, they create Spangle galls on the undersides of those leaves. The galls look a little like inverted saucers, with a slight hump in the middle. They are hairy and often quite a bright pinkish red to begin with, maturing eventually to a dull brown. Once mature, in late summer, the spangles detach and fall to the ground to be covered by the leaves of the oak, when they fall in autumn. The larvae overwinter in their cosy spangles, hatching in the spring when, without the need to mate, they lay their eggs on the oak’s leaves and catkins, thus producing the alternate generation of Currant galls. And so the cycle continues …
Happy St Patrick’s Day! It seemed appropriate to honour St Paddy and those from the Emerald Isle with a blast of green today. I think Goethe got the feel of green exactly right in his Theory of Colours:
The eye experiences a distinctly grateful impression from this colour. If the two elementary colours [blue and yellow] are mixed in perfect equality so that neither predominates, the eye and the mind repose on the result of this junction as upon a simple colour. The beholder has neither the wish nor the power to imagine a state beyond it. Hence for rooms to live in constantly, the green colour is most generally selected.
And this is why walking in a forest of green trees, sitting on a grassy lawn, or strolling in a garden all make us feel happy. Now, where did I put that paintbrush?
‘We find from experience that yellow excites a warm and agreeable impression…. The eye is gladdened, the heart expanded and cheered, a glow seems at once to breathe toward us.’ ~ Johann Wolfgang von Goethe, from his Theory of Colours, published in 1810.
I’m moving house in a couple of weeks so I’ve started saying goodbye to some of my favourite local spots – not that I won’t ever see them again, as Roath Park will still be a short 30-minute train ride away, but now it’s just a 5-minute walk.
I’ve taken lots of photographs of Roath Brook in the 17 months I’ve lived in this area, mostly from a similar angle, standing on one bridge and looking towards the other, ’cause it’s just such a lovely scene. Here are just a few of those shots, mostly taken in autumn and winter as the leaves obscure the scene in spring and summer.
From the poem ‘Autumn’ by my delightful cousin Jan Gemmell:
Autumn is fast approaching, and the leaves turn into gold,
The days becoming shorter, the soil becoming cold,
Yet it’s not all that depressing; glorious gifts abound,
There’s much to fill the heart with joy if one just looks around.
The trees are shedding mantles to prepare for season spring,
Brisk winds rustle dying leaves, and make the wind chimes ring,
I clothe my feet in sturdy shoes and crunch the falling leaves
Which tumble from the bushes and whirl around the eaves.