THE wintry weather that bit hard at the beginning of the month coincided with the opening of the first blackthorn blossom.

Closely related to the domestic plum, this tough shrub is one of the first to show its buds to an unfriendly world and one of the main reasons why sloe berries are such an erratic crop in our part of the country, although they do wonderfully well in the milder maritime climate of western England and Ireland.

Although a member of the huge rose family Rosacea, apart from the flowers that resemble a miniature dog rose, blackthorn has little resemblance to its cousins.

In times past, the wood was made into a variety of implements from clubs to walking sticks, but its main use was for hedging and fencing. The shiny black stems and twigs are armed with strong and impressively sharp thorns.

It would take an extraordinarily thick-skinned beast to push through a well-established blackthorn hedge and, as I know to my cost, it can penetrate all but the most rugged tweed cloth. The bitter foliage is also a deterrent to browsing animals.

Blackbirds and thrushes love sloes, and the two have a close association. In order to ensure the seeds are spread far and wide and fall to the ground in the best condition possible, the berries are edible only after they have been thoroughly sun ripened and then frosted to break down the acidity to an acceptable level. When the berries are just right, they are eaten by the birds, pass through the digestive system and the stone (seed) is expelled along with a package of fertiliser.

In ideal conditions the seeds germinate readily and within a decade an impenetrable thicket will grow, providing an excellent habitat for nesting songbirds, particularly those that may be predated by crows or magpies, or by opportunist foxes that are adept at climbing to reach food but will avoid the thorny blackthorn.

One of the most successful shrubs in the countryside, blackthorn has hedged its bets in that it is also wind pollinated and, should the blossom fail, it can resort to propagation by runners.

The blossom of this extremely productive shrub, although tiny, is quite beautiful, and the fact that it flowers in profusion long before other shrubs have even begun to swell is in its favour both to people who delight in the sight of the bush dressed overall like a huge bridal bouquet and to the natural inhabitants of the countryside.

Bumblebees are among the earliest insects to be out and about, seemingly able to rev up and take off in all but the most inclement spring weather, and the nectar-rich blackthorn blossom and protein-packed pollen provide vital energy for them, and for the early butterflies too.

Fewer animals are grazed out in the fields these days, and stock-proof hedges are no longer as necessary as they once were.

In the 1970s and 80s, thousands of miles of hedgerows were grubbed up, paid for with taxpayers' money, and wire fencing is now the preferred means of enclosing an area of land, but it does nothing to enhance the countryside.

Fortunately, the Government has just announced a change in the subsidy system that will give money to farmers and landowners to manage the land in a more environmentally friendly way.

Not before time, we look to be moving away from destructive agricultural subsidies and towards a more holistic method of land management.

In places where traditional stock-proof hedges remain the number and variety of wildlife species are increased.

In Buckinghamshire and Bedfordshire, for instance, where there is a considerable amount of blackthorn the brown hairstreak butterfly and the black hairstreak butterfly, two insect species dependent on this shrub, have their national stronghold.

They have not been able to expand their range because there are so few continuous blackthorn hedges in other areas.

At the moment, the eggs of both butterflies are tucked up under the leaf buds of the blackthorn waiting for spring to wake them from dormancy. But it makes you think how a simple change in the subsidy of hedgerow management may mean a more certain future for these two small butterflies and a better future for more than half of all native butterflies now on the danger list and many of the once common species that are now relatively rare.

I was at Tring Reservoirs in Hertfordshire a couple of weeks ago to record a programme for BBC local radio. The reservoirs are always fascinating as there's always something different to see. Dug by hand in the 18th century to provide water for the Tring Steps, a system of locks that takes the narrow boat traffic on the Grand Union Canal over the Chiltern Hills, the banks are now largely naturalised and bordered by trees, many of them clothed in a lush blanket of ivy, one of the most misrepresented and under-rated plants in the whole countryside.

Revered by the Druids, who thought it magical, the dense foliage shelters many species of wildlife, provides nest sites for birds and hibernation places for butterflies, and is the larval food plant of a number of insects vital to the overall health of the countryside. And still we treat it as if it were some alien invader.

Can I make a plea on behalf of the ivy?

Please do not cut it down.