The glass tube with which I measure the rain for Met Éireann is kept safely sheathed on the upturned beak of a dolphin's skull sitting on a bookcase (there evoking, however indelicately, a tall crystal condom). Over the years I have broken a tube or two – they roll off things – and I might have been excused the other morning for dropping yet a third.
The glass measures up to 10.5mm of rain at a time, drained from a big bottle set beneath a bronze funnel in the lawn. Four or five point something means we had a decent shower yesterday; 10 or so, that it was really rather wet. The weight of the bottle the other morning warned of something extraordinary.
It took eight pours to measure 83.5 mm, or about as much rain as might fall on us in a whole month of spring. A lingering unease about my accuracy was set at ease when friends on Inishbofin, the comparatively low island out on our horizon, reported 75mm – their own ultimate total in 24 hours.
There was a time when such a flood in the hill stream would have worried us in the night, as rocks rolled under the bridge with detonations like colliding cannon balls. We built an early rampart of boulders below the gable, to swing such inundations through the hedge. Today, double-glazed windows exclude not only birdsong, which I regret, but the more disturbing reverberations of storms and floods. A tangle of trees also muffles the stream, its normal flow once such a lively melody to our days.
With anoraks in several weights, we live with the new rain of climate change, among the first to feel its weight as obese and supersaturated clouds roll in. In between, however, the sun holds to its post-equinoctial descent, delivering the season’s splendid textures and smouldering colours in the land.
The rain has left the acre's hedges dripping and brambles soar over them like the grapnel-lines of a medieval siege. Most of the berries they offer are still meanly tight, where ripening at all. But the arching new growth stretches leafy tips down to the soil, there to take root and leap up again next year. It seems the ambition of Rubus fruticosus, the common blackberry, is to take over most of this island. It is helped by a climate that lets it keep leaves through the winter, gathering fresh vigour for the spring
The bramble's main strategy, one might think, is to have its seeds spread by wildlife, as animals and birds feast on its berries (many fox droppings are now a mass of pips). But the seeds are produced asexually – berries form even when the flowers are shielded from pollinating insects – and few actually succeed in making fresh plants. Meanwhile, the clonal march of briars, in varying habitats and micro-climates, has created at least 80 Rubus micro-species in Ireland – perhaps several in one stretch of hedge. There could be more to come, as more botanists master a notoriously difficult taxonomy.
Even ordinary humans, gathering blackberries for pies and jams, will notice the more obvious differences between one roadside bush and another. On one, the berry is small and made of many tight-packed segments. On another it is huge, with few but enormous segments, bursting with juice and sweetness like a bunch of glossy grapes.
The briars, too, can differ greatly. One is as thick as your thumb and claws its way up the hedge with savagely hooked prickles. Another arches its stems in quite a different way and the prickles are smaller and finer, and point at a different angle. There can also be a host of differences, often minute, in the size and shape of leaves.
Not all Rubus species are blackberries. Rubus idaeus is the wild raspberry, bright red or yellow and quite common in the woods, thickets and riversides of our northern counties. There, too, in wet peat on one north-facing slope in the Sperrins, Co Tyrone, grows Ireland's rarest Rubus of all – a single colony of the cloudberry, Rubus chamaemorus.
This species is almost unique in these islands for growing above 350m and its berries – first red, then orange-yellow – are an occasional treat for hillwalkers in upland Scotland and in the English Pennines. The Sperrins colony, however, appears to be a last remnant of Ireland's vegetation in times of Arctic cold.
The colony is hard to find, even for a botanist, mustering perhaps a score of shoots less than 20cm long. Their small leaves are almost submerged in the close growth of other plants and have never been seen with flower or fruit: the colony may well be a last male clone without hopes of either. The Ulster botanist Dr Ralph Forbes finds its survival over 12,000 years of plant competition quite remarkably stable, especially now on peatland that is "weathered, grazed, burnt, trampled and . . . seriously eroding". But further global warming "may finish the job".