Michael McCarthy: Why the blackthorn is a herald of spring

Some signs of spring are particularly moving because they have remained free from the clutches of cliché. I yield to no-one in my appreciation of primroses and cowslips, even of municipal daffodils, God bless them in their regimented beds, but there is another mark of the shift in the seasons which stirs something deeper in me, and that is the blossoming of the blackthorn.

My impression is that most people, in these days of urban existence, have no idea what the blackthorn is. Certainly, I've never seen a picture in a newspaper of it flowering with a caption shouting Spring Is Here! like I've seen a million such captions of blossoming cherry trees. And I have to say I came to an appreciation of it myself rather late. But now I find it affecting to a degree.

Last week I went to Brighton to cover the launch of the Green Party election manifesto – Greens are drawn to Brighton, the place where old hippies go to die, like Jews to Jerusalem or Muslims to Mecca – and I went by car because I had to go on to a couple of other places, and on the way back to London the A23 was bordered with blossoming blackthorn for mile after mile.

Every few yards, for ten miles, twenty miles, thirty miles through the Sussex countryside, there seemed to be a blackthorn bush dressed from head to foot in white, and I wondered how many of the drivers pelting along the dual carriageway were appreciating its spectacularly ornamented flanks.

Eventually I found a blackthorn-fringed lay-by, pulled in and greedily broke off two of the blossoming stems and drank deep of their honey scent. They travelled with me on the dashboard all the way home.

There is something special about their beauty. A blackthorn bush in flower looks as if it is covered in hoar-frost, rather than weighed down with fat hanging blossoms in cherry-tree style; it looks like trees do on those winter mornings when you wake after a night of freezing fog and every black branch seems to have been dusted with sugar. Eventually (with a little help) I realised the reason: because, unusually, the flowers on the blackthorn appear before the leaves, the whole arrangement is more spindly and delicate, bare branches that seem to have been spayed with white.

There are other reasons to appreciate it. The principal one is the fruit, for the blackthorn produces sloes, those small black plums which are mouth-puckeringly astringent until the frosts get at them in October. Then they sweeten and can be used to make sloe gin, one of Britain's great native drinks, up there with the fruit eaux-de-vies of France; in fact I would go so far as to say it is sensational stuff, and never better tasted than out of a hip-flask on a walk on a winter's day. Make me a present of a bottle of sloe gin and I will be your friend for life.

Another benefit of the blackthorn is its wood, which makes prized walking-sticks, and in Ireland was traditionally used to make the shillelagh, the fighting club. (Blackthorn plays a substantial role in Gaelic folklore, where it is considered almost as magical a tree as the rowan.) And a third benefit is one you need to be something of a nature nerd to know about, which is that blackthorn is the larval food plant of two of Britain's more uncommon butterflies, the black and brown hairstreaks.

The black hairstreak is a bit boring, to be honest, but the female brown hairstreak is one of our loveliest insects, with glowing golden bands across her brown forewings, and you can only see her when she descends from the treetops in late August and September to lay her eggs on blackthorn twigs. One of my most prized possessions is a painting of a female brown hairstreak next to a bunch of ripening sloes: autumn glory, I think when I look upon it.

But the blossoming moves me most. It is early, usually appearing in mid to late March (it was nearly a month late this year), and sometimes it bursts out in a premature warm spell which is followed by a resurgent freeze, and this final flourish of the cold when spring has already begun is known in the countryside as the blackthorn winter. (I first heard the term from a water bailiff in Devon.) Blackthorn winter strikes me as one of the most evocative names in the calendar – sooner or later someone is bound to use it as the title for a novel – and it is certainly one of the most captivating moments of the year, when despite the chill of the air, the thorn branches frosted in numberless small white petals remain defiant signals of the warm times to come.

A friend who is a fisherman phoned me on his mobile from the banks of the River Avon in Hampshire on Wednesday and said: "I've just heard a cuckoo. I thought you'd like to know." Last year I published a book, Say Goodbye To The Cuckoo, about the fact that Cuculus canorus is declining precipitously in Britain, along with a number of the other migrant birds from sub-Saharan Africa which make their great journeys to us every springtime, such as the turtle dove, the nightingale, and the wood warbler: they are all plunging in numbers precipitously.

A year on, what is the position? Unfortunately, the declines seem to be continuing unchecked. Nobody really knows the reasons, but at least scientists are now trying to find out what they might be, and the British Trust for Ornithology has launched a major research project on the issue, entitled Out Of Africa, which is examining possible causes for our migrants' decline in the African continent itself. Look up Out Of Africa on the BTO website and you will be led to a charming section which includes video profiles of all the threatened birds, cuckoo included.

m.mccarthy@independent.co.uk

For further reading

British Trust for Ornithology Out of Africa Appeal: www.bto.org/appeals/out_of_africa_appeal.htm

Monday: Media Studies