30 JULY 1977, Page 21

Herbary

Brian Inglis

Guide to Medicinal Plants Paul Schauenberg and Ferdinand Paris (Luttorworth Press £5.95) I began by looking up 'Lettuce' — a curious choice, you may think, but curiosity was in fact what prompted it. A century ago, James Johnston, Professor of Chemistry at the University of Durham, remarked in his Chemistry of Common Life that 'the juice of these plants, when collected and dried, has considerable resemblance to opium'; adding that it acte,d like opium — 'eaten at night, the lettuce causes sleep; eaten during the day, it sooths and allays the tendency to nervous irritability'. In an unguarded moment I remarked to Bill Grundy that this put the lettuce in a new light. Did I not recall, he replied witheringly, what had happened to Beatrix Potter's rabbit? A surfeit of the stuff, sending him to sleep, had nearly resulted in his becoming one of the ingredients in Mr. McGregor's pie.

It was not, at first, easy to find 'Lettuce', as the chapters in this encyclopaedia are divided up with such titles as: `Plants containing sulphur heterosides', 'Plants contining cyanogenic heterosides', and 'Plants containing simple phenolic heterosides.'

But Lactuca sativa (not to be confused with Lactuca virosa, the greater prickly lettuce, which has very different properties) appeared in the index under 'Plants containing vitamins', which was reassuring — though not for long. Lettuce is credited by the authors with being a rich source of vitamins; it even has a provitamin — an adolescent vitamin, that is, which refuses to behave according to the conventions. Lettuce also provides glucoquinones, whatever they may be. But in the seotion 'Applications', which accompanies each plant, sedation is not mentioned. Rather the contrary: in homeopathy, we are told, 'a tincture extracted from the whole fresh plant is used in the treatment of impotence'.

So lettuce is an aphrodisiac ... It is, in fact, listed as such in the glossary, along with Heracleum spondylium — the Cow Parsnip, or Hogweed; Foeniculum Fennel; and Satureia hortensis — Savory ('an excellent anti-diarrhoeic, nerve stimulant and aphrodisiac'). And alongside these there are the entire contingent of plants listed as containing sulphur heterosides, garlic, shallots, onions, leeks, chives, radishes, mustard, cress, rape; even, so help me, turnips. And, as an afterthought, wallflowers. All, apparently, are venereal in effect, if you know how to use them.

Here is the catch. Though each plant has its 'applications' — fennel, for example, in addition to its capacity for sexual arousal, is

'carminative, stomachic, expectorant, diuretic, galactogenic and anti-spasmodic' — the authors do not provide instructions how the plant can be put to the required use. A separate section deals with 'recipes', and, apart from the fact that impotence is not listed among the disorders for which the recipes are designed, they are not of a kind which many of us would find easy to make up. To treat menstruation disorders, for example, two recipes are given, to be taken alternately in the form of tisanes: one containing Mugwort, Shepherd's ,Purse, Roman Chamomile, Rosemary and Sage, in equal proportions; the other, Silverweed, Lady's Mantle, , Woodruff, Cinnamon and Tormentil. Three • tablespoons of each tisane, the prescription says,, should be simmered for five minutes, and a cupful drunk every half-hour. But though a section at the end of the book gives attractive little coloured illustrations of many of the plants described in the text, few of us, I suspect, will be able to find them on country rambles; and your local chemist is unlikely to have them in stock.

'Perhaps this is just as well. The authors do not attempt to come to grips with the chief unsolved problem concerning plant drugs: how far are their therapeutic properties related to the actual chemical constituents, and how far to some undiscovered sympathetic force, such as some homeopaths accept?

The tendency has been to concentrate on the chemistry. But here, the story of the discovery , of tranquillisers provides a cautionary tale. The root from which they were derived had a long history of use as a narcotic. But when trials were made of the root itself, as distinct from the chemical isolated from it, they appeared to show that it had no narcotic properties. Why? Perhaps— it has. been surmised — because the trials were undertaken on subjects who had no particular expectations from the treatment.

If so, plant drugs work because we expect them to work. Everybody knows this is true of the removal of warts. According to the authors, the plants of choice for this purpose are the greater celandine, garlic, and marigold: presumably a French selection. In my childhood, the dandelion was favoured. But scores of plants have been successfully used for this purpose. Every region, probably, has its own speciality. Not the plant itself, but the rapport with it, does the trick.

In some parts of the world Cannabis saliva, Indian hemp, is used for the purpose here listed, as 'excitatory and hallucinogenic': but in others it is used as a tranquilliser. In some parts of the world .opium derived from the Papaver rhoeas, the poppy, is used as here listed, for sedation; in others, as a stimulant, taken periodically during the day much as we here take cups of coffee, to ward off sleepiness. Drug effects are highly subjective. A book of this kind, therefore, though full of fascinating information — and often funny, though unintentionally — is not to be taken seriously.