Raiders of the lost lichen strike gold

Another LifeIt was seven feet up in an old, gnarled and very prickly whitethorn in a winter-flooded pasture in south Cork. In summer the leaves would have hidden it, but on a bare winter branch the golden-eye lichen, Teloschistes chrysophthalmus, positively glowed - fluttering its eyelashes, one might almost say, at a thoroughly gobsmacked English lichenologist.

I wrote here a couple of weeks ago on the progress of LichenIreland, the intensive, 26-county survey of a somewhat neglected legion of our flora. But it is worth coming back to the subject to celebrate something as beautiful - and exceedingly rare - as the golden-eye, and to thank Vince Giavarini, from Dorset, for finding it, and Robert Thompson, Ulster's gifted nature photographer, for sticking his stepladder deep in the mud to climb to sprays of thalli (fruits), the size of bright sovereigns. They have added the 1,208th species to the island's lichen database.

Golden-eye, as Giavarini says, is not only one of the world's most attractive species, but "the Holy Grail of the lichen world for which bottles of single malt whiskey have been offered as an enticement to searchers". It has also not been seen in Ireland for 150 years. By extraordinary coincidence, last year produced two similar discoveries - one in an orchard in Herefordshire and the other on Guernsey, in the Channel Islands - both, significantly, after a similar sort of absence.

The Cork lichens are perhaps three or four years old, and it is well worth visiting the website of Guernsey's natural history society -

www.societe.org.gg/press/20071203 _lichen.html - to see the golden-eye in its fully developed glory. The president of the society spotted it on a bush during a walk on the island's cliffs.

While the scientists aren't swearing to it, the fact that the species is more at home in the Mediterranean makes the finds a clear candidate as a sign of global warming. But the lifestyle of a lichen makes its dispersal a distinctly chancy affair.

A lichen is not a plant but a symbiotic partnership of a fungus with a colony of algae or cyanobacteria (sometimes both). It reproduces in two ways - by windblown spores from the fungus that meet up by chance with the right algal or bacterial partner, or, more reliably, by ejecting particles in which cells of both partners are bonded, called soridia, that also fly on the wind.

That Irish lichens can be brilliantly coloured, as well as subtle and exquisite shades of grey, we know from the blazing oranges and reds of Xanthoria and Caloplaca on seaside rocks (especially glorious where fertilised by perching seabirds). But some colours can still amaze. A photograph came from a reader, Mark Shorten, whose dog had brought him a stick near the shore at Mizen, Co Cork. It was a long-fallen branch of furze, coated with lobes of a brilliant blue lichen that neither he nor I had ever seen.

Vince Giavarini, consulted, knew it as cobalt crust, or Pulcherricium caeruleum, a lichen that colonises the underside of fallen trees such as hazel and ash - "a shy species", as he said, that will happily grow in the dark. It is the most intensely blue of all lichens (nearer indigo than cobalt, depending on its moistness) and its beauty is expressed in its Latin name - think of "pulchritude".

LichenIreland (find it at www.habitas.org.uk) is funded from north and south but co-ordinated at the Ulster Museum, where Dr Damian McFerran runs the already-extensive Cedar nature database. He enlisted lichenologists from the UK to help Irish fieldworkers record the distribution of perhaps 50 to 100 species in each of the island's 10km squares.

Even after three years and some 17,000 records, there are still more than 200 squares without any lichens on the database. There are particular gaps on the coasts and uplands, and the woodlands are still waiting for a systematic search. It may take another two years, but Ireland's richness in lichens, born of rare clean air and moist winds, is worth the effort.

MARCH WILL BRING National Tree Week and a whole programme of events to get families out under the greenwood boughs. But mid-winter is also the time for a bit of, at least metaphorical, tree-hugging.

This is the light for the shapeliness of trees, the texture of bark, the massive dignity of age. Also for realising their tenacity and right to a long life, even when hollow or pollarded.

I talk, of course, of broadleaves. But there's nothing like a misty hill of conifers for magical swathes of mid-winter mosses and lichens. Think small, look close - take a magnifying glass for the details.