Tapping the veins of folk wisdom's

Like the falling apple that may or may not have led Newton to significant thoughts about gravity, the cluster of conkers that whizzed past my ear on a windy day in Castlebar reminded me to consider ethnobotany, pharmacognosy, phytotherapy, to trot out only three long modern words to do with one ancient subject: herbal medicine. The sight of horse chestnuts in their prickly, split-open shells - still more, the feel of that ineffably smooth nut-skin and the cool, white felty stuff it nestles in - still works a nostalgic magic about conkers and schooldays (now, apparently, all quite meaningless in the technoworld of adolescence). But in addition, my mind dredged up an image from a company video, of great drifts of the nuts being wound into the maw of a shiny, steel laboratory vat. At the Klinge pharmaceutical factory, down in Killorglin, Co Kerry, the season's conkers are being processed for a treatment for varicose veins and piles. The astringent tannins, flavonoids and saponins of horse chestnuts help the vein-walls to strengthen and un-knot themselves. To Germans there is nothing at all extraordinary in harvesting plant extracts in this way: their country is the world's largest market for herbal products, with a trade worth more than £1.4 billion a year.

Nor should we assume that Ireland must be lagging behind in the R&D of the new and rapidly expanding phytotherapy (phyto = plant). In Trinity College's School of Pharmacy in Ballsbridge, Dublin, strains of Irish yew are under test for their yield of taxol, a valuable drug in treating ovarian and other cancers. American demand for taxol is so high that it is actually endangering the wild yew on the hillsides of northern India and Nepal. The Irish yew, too, is rather rare in the wild, but if it out-yields the European yews in taxol, this may lead to the planting of new, pharmaceutical forests, at once gloomy and beneficent.

The School of Pharmacy is also working with a European group called ESCOP to produce 50 monographs on the most widely-used herbs in Europe, examining their chemistry, dosages and side-effects, if any. Watching the enormous growth of plant-based medicines, the EU is anxious to bring scientific standards to bear to make sure that the right plants, with the right chemicals, are used in the right way. With this sort of laboratory quality-control, the real worth of herbs such as burdock, lovage, yarrow, ox-eye daisy, parsley piert, St John's wort, hawthorn and dozens more can be established, and their efficacy guaranteed.

It was mainly the difficulty of standardising and guaranteeing the quality of plant medicines that led to the production of synthetic drugs by the pharmaceutical industry after the second World War. The current rediscovery of medicinal plants still has to contend with the scepticism of doctors for who the "folk" traditions of some herbal medicine are too closely identified with wishful thinking (the placebo effect) and an unhygienic shamanism.

Folk medicine is a tantalising repository of clues to reputed or potential cures and the archives of Irish folklore have been closely sifted for herbal remedies ("the wealth now lying hidden in the Gaelic Nature Creeds", as one hopeful nationalist doctor, Michael Moloney, put it in 1919). Dr Desmond Corrigan, head of pharmacognosy in the School of Pharmacy, has made a special study of documentary herbal sources and folklore records.

A big difficulty has been the precise botanical identity of the plant being used. Many local names have passed out of currency (especially in Irish), and few herbalists from the past were thoughtful enough to stick specimen plants in their records. But the more recent researches have shown many rational matches between the folk-uses of particular herbs and what is now known of their properties.

Among Co Wicklow cures for whooping cough, for example, is sundew. Growing in the bog, it catches insects with its sticky leaves and digests them - but it is also antibacterial and has the ability to stop spasms. In Irish, plantain is the healing-herb, slan lus; an extract of the plant has been patented in Europe to promote clotting and wound-healing. Selfheal, supposedly "good for the heart", has compounds similar to those of ginseng and others similar to the compounds in hawthorn that are known to be clinically effective for mild heart conditions.

Some years ago, the discovery that the Madagascan periwinkle contained anti-cancer agents dramatised the need to conserve the world's plant species. It produced two drugs successful in treating leukaemia. In Jamaica, the same plant has a folklore reputation as an oral insulin-substitute, and some of its components do, indeed, lower blood-sugar. A compilation of traditional herbal cures in Co Cavan, in the 1970s, mentioned the ordinary - but related - garden periwinkle (now sometimes naturalised at roadsides) as a diabetes cure.

ONE great advantage of synthetic drugs is that most are manufactured from abundant elements. The rocketing market for herbal preparations is threatening the wild stocks of many species, especially as these become fashionable. Along with such "feel-good" elixirs as Chinese ginseng, the plants under pressure include some which depend on dwindling habitats - among them, bog bean (Menyanthes trifoliata), the familiar pink-flowered aquatic plant of Ireland's moorland pools, said to ease rheumatic pains. St John's wort (Hypericum perforatum), common on drier ditches in our limestone midlands, seems set for huge demand as a safe alternative to Prozac in relieving depression and anxiety. Once again, Ireland would seem unusually well-placed to trade on its largely undeserved "green" and "folk" images in the cultivation of sought-after herbs. To farm wild plants reliably is by no means easy: Sean Boylan, the Co Meath herbalist, is unique in his flowering fields at Dunboyne. But we do have the semi-wild, marginal habitats (not to mention the cut-away bogs for Menyanthes) in which many valuable herbs will thrive, and the enthusiastic scientific expertise of Desmond Corrigan, his students and colleagues - in a word, the pharmacognoscenti.