Not before time, historians are turning their attention to the often remarkably involved careers of the more familiar fruits and vegetables. For long, Redcliffe Salaman held this field alone, with his justly-renowned History and Social Influence of the Potato. Smaller-scale and little-known by comparison, but in its unambitious way hardly less fascinating, is N.W. Simmonds’s monograph on bananas, with its thought-provoking insights into early human migrations derived from the study of present-day distributions of the banana’s varieties, each of them reproducible only vegetatively and so totally dependent on human beings for their spread.
Professor Foust is a worthy successor to these men. A specialist in the out-of-the-way topic of 18th-century Russo-Chinese trade, he became intrigued by the salient part played in this by rhubarb. The trail took him deep into unfamiliar botanical and medical territory, from which he has emerged triumphantly with this stunningly comprehensive story, the product of a ransacking of the literature in several languages and of three sub-disciplines at least. Seventy pages of end-notes and a further forty of bibliography do not ordinarily act as bookends to a compellingly readable text, but they do here. The Wondrous Drug is a craftily-constructed tale of Oriental elusiveness, the step-by-step unravelling of a mystery.
Like bananas, rhubarb has the misfortune to be one of those automatic joke words, its mere mention almost guaranteed to raise a smirk. But that it deserves to be taken seriously the author quickly convinces us, for whereas today we tend to think of it primarily as a dessert, consuming its leaf-stalks, in the past it has predominantly been seen as a medicine and it was the root that people valued. Indeed, as Foust points out, ‘there probably has been no medicine that has brought greater relief to larger numbers of people.’ A purge exceptional in its gentleness (and thus safe for small children and even for pregnant women), it also possesses tannins that have an astringent, binding effect. In the days when purging and bleeding were the standard way of treating illness a herb that had such virtue was bound to be in almost unlimited demand.
Unfortunately, though, it remained for centuries frustratingly hard to come by. Its dried roots reached the Mediterranean world only after a long and doubtless often hazardous journey from areas further east, and they were never obtainable in anything like the quantities that the market could readily have absorbed. Consequently they were to be had only at a very high price. That did the herb no harm at all, of course, in the eyes of the apothecaries and druggists, who always tended to favour costly imported botanicals – despite a school of belief that it was the local herbs which best suited local constitutions (for had they not been placed by a beneficent Deity where they were conveniently available for gathering, complete with built-in clues to the ailments for which they were intended?). Even if the dealers and dispensers had not promoted imports at the expense of what was indigenous, we can be sure that the more affluent of their customers would have insisted on them: for apart from the fact that the mere ability to afford the scarce and the exotic conferred a social cachet, there was a long-standing faith in the wisdom of the Orient and in the inherent superiority of anything that people went to so much trouble to bring from such a distance.
It must have helped, too, that rhubarb had the imprimatur of the Classical writers on herbs, whose presumptively hard-won cumulative lore was to have the strength of holy writ till long after the Renaissance. The great Dioscorides, and after him Pliny, had trumpeted its power to assuage the usual wide range of afflictions, while correctly identifying it as a cathartic first and foremost. They knew it as a plant that came from the lands beyond the Bosphorus – from what the Greeks and the Romans understood, vaguely, by ‘Asia’. Uncritically, their successors assumed that it was therefore indigenous to the vicinity of the Black Sea, to the region known to the Romans as Pontus. The particular kind of rhubarb that found its way to Western markets in greatest quantity accordingly came to be distinguished as ‘rhapontic’. This was held in higher esteem than ‘rhabarbarum’, which was believed to grow somewhere beyond Barbary (William Turner in the 16th century thought the ultimate source was Ethiopia). But neither of those commanded anything like the prestige or the prices of what was popularly known as ‘Chinese’ rhubarb – though whether it actually came from China was very far from certain. What made this third kind so highly prized was its reputedly much greater effectiveness: it was indeed about twice as potent as ‘rhapontic’, as was later to be established.
The Chinese are known to have grown and utilised rhubarb (they called it ‘the Great Yellow’) from earliest recorded times. There is reasonably good evidence that roots from there were reaching Europe by the eighth or maybe the ninth century, probably via the Arabs, the main transmitters to Christendom of the medical learning of the ancients. A century or two later an established trade was in being across South-West Asia to Egypt and the Levant, and by the 15th century the distinctive spongy roots of the Chinese plant or plants were advancing over most of Europe.
As physic gardens spread, herbalists vied with one another in bringing rhubarb into cultivation. The kinds they were able to obtain for this purpose, however, proved successively disappointing. For a time high hopes were entertained of ‘rhapontic’, but by the end of the 17th century these had been effectively dashed. It was Chinese rhubarb that they had to have if they were to be in a position to claim that their gardens supplied the choicest items in the contemporary pharmacopoeia.
For a long time the only European to have seen rhubarb actually growing in China was Marco Polo, in 1295. He had described it as ‘bigge as a mans thigh or legge’. Around 1600, Jesuit missionaries succeeded in establishing that its cultivation was concentrated in certain western parts of the country, whence it was brought down to the coast and then taken overland to the West by Moslem caravans. Some fifty years later, one of these missionaries at last set eyes once again on the living plant and this time provided a good description. The yellow roots, sometimes as much as three feet long (and certainly as large as the arm of a man, he confirmed), were cut while fresh and usually in winter, when they were at their most efficacious, dried first on long tables and then in the wind, the direct heat of the sun being carefully avoided.
At this point the Russians enter the story. Well-versed in such esoteric sources as the custom books of Tobolsk, Foust is here on home ground and at his most impressive. He relates how the importing of the Chinese roots early became a lucrative monopoly of the Tsarist court, which successfully pursued a policy of strict rationing in order to keep up prices. Anyone caught smuggling rhubarb paid with his life. In 1727 Peter the Great tried relaxing things, only to touch off such a tremendous surge in trade (as evidenced by the London customs records) that the court came to the conclusion that the monopoly had been very much to its financial advantage, and acted accordingly. This time, however, it also took the important step of strictly controlling quality as well. In consequence, Russian (or Crown) rhubarb gained a reputation in Western markets, which helped it to maintain its position in the face of low-priced imports that were now beginning to reach the West from China via India. In the end, though, inefficient marketing and over-rigid pricing did what the various East India companies had never succeeded in doing: the monopoly had to be abandoned, a century and a quarter after its original introduction.
From 1740 onwards, the world trade in rhubarb increasingly came to centre on London, as immensely large quantities poured in, particularly from India. Half of what arrived was passed on elsewhere, the other half kept for a home market greatly enlarged and broadened as the price of ‘India’ rhubarb progressively fell.
The heavy import bill now led to a redoubling of efforts to find the ‘true’ rhubarb, in order to raise it locally as a crop. The story from this point on has striking parallels with the later attempts to run to ground the best-yielding strains of cinchona in the forests of Bolivia and Peru. One kind after another was first triumphantly discovered and laboriously taken into cultivation, only for further and better ones to materialise a few years later. At the same time what ought to have been a straightforward process of making a previously rare medicine available for the benefit of all mankind was chronically distorted by the tenaciousness with which the plant’s homeland strove to preserve its profitable, nature-given monopoly.
In 1734 the Chelsea Physic Garden received from Leyden seeds of an undulate-leaved rhubarb from somewhere east of the Urals: but the claims which Philip Miller was excitedly led to make for what came up from them proved, alas, ill-founded. Linnaeus had better success when he described another rhubarb from Russia as Rheum palmatum in 1750: with the backing of his authority this was to remain Europe’s favourite candidate for the ‘true’ plant for the following half-century. Seeds obtained from Sweden and from Russia were widely distributed in Britain and led to mass cultivation in the University Botanic Garden in Edinburgh. The Society of Arts, that enterprising body, then took over and used its system of awarding medals to promote commercial production. Once again, however, hopes were dashed. Not even this plant could measure up to the standards set by the Chinese roots; moreover, it had the drawback of not invariably breeding true (it was only much later, well into the next century, that it was discovered that propagation by root division was essential to preserve the type). Sales proved disappointing, and R. palmatum had largely ceased to be grown before very long.
Undaunted, the searching went on. Further species were found in the Himalayas – and in turn proved disappointing medicinally. Another was obtained at last from China itself, after war in the 1860s had opened up its interior to Westerners. That too, while spectacular ornamentally, was to turn out a dud as a commercial herb. Yet another was then brought back from the very area of China long reputed to be the source of the best roots that found their way to the European market. Very understandably, this was acclaimed as the ‘true’ rhubarb finally run to earth. Yet even this proved open to dispute and its sponsors in St Petersburg failed to convince the rest of Europe that it now possessed the Holy Grail.
By that time, in any case, the awful truth had begun to dawn: perhaps there was no single ‘true’ rhubarb after all. Instead, various kinds might be more or less effective depending on how they were prepared or on the conditions in which they were grown. Unexpectedly, it turns out that this question is still unresolved today. Granted that the best rhubarb comes from the west of China, what indeed is the factor responsible? Is it the temperature? Is it the altitude? Is it the soil? Is it subtleties in the harvesting and drying? Or is it some combination of two or more of these? The riddle might be easier to solve if only the phytochemistry of the rhubarbs was better understood. But here again all is complexity: for the pharmacologists the difficulties have hardly been less than they have been for the taxonomists.
In conducting the reader on this far-reaching tour, Foust goes down several interesting side-roads. We learn in some detail about the history of purging, about botanical illustration and in particular about the anti-adulteration movement. The drive to establish the purity of rhubarb gave a big fillip to this last, an accidental by-product comparable in its way to the stimulus that the Mid-Victorian fern craze gave to the art of nature-printing.
It is hard to know which to admire more: the sheer breadth and depth of Foust’s research or his skill in marshalling the evidence and making out of it such an engrossing narrative. So dazzling is his mastery of his subject that it is something of a small triumph to be able to point out an error: it was not James Sherard who was the Consul at Smyrna but his even more avidly botanical brother William. Curiously, the author has conflated the two and consequently misidentified the person whose name is commemorated in the Oxford Chair.