The silver birch at the ditch was sporting its first leaves on sheltered branches, along with small catkins, stiffly arched and green. Down in west Cork the same day would have found birches fully clothed, catkins dangling in primrose-yellow bloom to offer pollen to the bees. And up in the glens of Antrim the leaves on birches would be few if any, and catkins still tight commas on the twigs.
Such intense acquaintance gives a quite new experience of trees – the astonishing bud-burst of the female sycamore, for example, flourishing fat catkins in rosy bracts, exotic as orchids; or the sudden, overnight leaves of lime, poised on ruby twigs like freshly emerged green butterflies. For science, however, phenology, studying the timing of changes in nature, is still a prime tool in charting the impact of climate change. Records of Ireland’s tree life, from budburst to fruiting to leaf fall, are produced in 16 phenological gardens across the country, planted with clones of European tree species as part of an international network. Eleven more gardens have native species alone.
From the heart of Dublin, meanwhile, comes a booklet to remind me of the pleasure of a lunchtime wander in spring around the grounds of TCD: the fourth and most polished edition of Trees of. Each of the scores of species has an aluminium number on its trunk, plus a profile in the booklet, a spot on its maps, and maybe one of the many fine images.