Scribblings on an aspen twig

June 12th 2015

Scribblings on an aspen twig

On 29th May (2015) Don O’Driscoll and Romany Garnett were carrying out, for the John Muir Trust, a bird survey on the north-eastern slopes of Quinag. On a crag not far from Cnoc Airigh na Beinne (NC2230) they came across a solitary aspen. Dead twigs on this tree were covered with what appeared to be black scribblings and Romany brought me a small sample, which David Haines has photographed.

These black markings are the tiny, crowded, linear fruiting bodies or lirellae of a lichen called Opegrapha atra. They belong to a distinctive group of lichens sometimes referred to as ‘Chinese writing’, which are usually found on trees, but also on rock. Seen through a x10 lens, the lirellae appear carbonaceous, with a central slit or furrow (lira is Latin for a furrow), and the scientific name of this species translates as ‘black hidden writing’, from their small size (up to 2 x 0.3 mm). O. atra is the commonest member of the genus, found mainly in coastal parts of the British Isles, usually on the smooth bark of well-lit trees, but occasionally on their twigs, as in this case.

Ian Evans

Lichen Opegrapha atra. Scale is in mm. Photo D. Haines
Lichen Opegrapha atra. Scale is in mm. Photo D. Haines
Lichen Opegrapha atra. Photo D. Haines
Lichen Opegrapha atra. Photo D. Haines

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