That roots grow downwards and shoots grow upwards is one of those obvious truths from observation that don’t seem to need questioning. But why this should be so, and the underlying biomechanics that make it so, are considerably less obvious. Many pioneering and yet very simply conceived and practical experiments on the mechanics of plants were carried out by an unassuming country gentleman, Thomas Andrew Knight (1759–1838), published in the transactions of the Royal Society and the Royal Horticultural Society, and collected in book form after his death. These potentially dry accounts are greatly enlivened by a ‘a sketch of his life’ by his daughter Frances (who married an Acton, of Acton Scott, in Shropshire, now mildly famous as the ‘Victorian Farm’) which precedes the papers.
The Knight family made a fortune in the seventeenth century by iron-smelting: there were Knights in Coalbrookdale before Abraham Darby I, II or indeed III, which is a salutary reminder that the Industrial Revolution did not spring from nowhere. By the time Thomas Knight was born, the family was sufficiently prosperous that he and his more famous elder brother could pursue their respective interests without the necessity of earning a living.
Richard Payne Knight (1751–1824) was fascinated by the classical world: he was educated at home, and went on the Grand Tour instead of to university. Travel in Italy hugely influenced his taste, and inspired the building of his new house, Downton Castle (no, not Abbey!) on his estate in Herefordshire. His classical interests extended (unusually for the time) to the non-rational, non-logical and downright weird aspects of Greek civilisation, and he became notorious for the publication of a book on the worship of Priapus in which he claimed a phallic origin for aspects of Christian symbolism. He pursued this vein of scholarship throughout his life, and it culminated in his 1818 An Inquiry into the Symbolical Language of Ancient Art and Mythology, but he was also a passionate collector of ancient and modern art, a member of the Society of Dilettanti, and a recognised arbiter of taste, especially in buildings and landscape.
In 1808, Knight made Downton Castle over to his brother Thomas and his family, retiring to a ‘cottage’ in the grounds. Thomas had been to school at Ludlow, and matriculated at Balliol College, Oxford, in 1778. Like Darwin a generation later in Cambridge, he seems to have spent much more time pursuing field sports than in study, though an extraordinarily retentive memory meant that he could accurately quote reams of poetry or prose, in Latin or English, throughout his life. Apart from a brief visit to Paris with his brother in 1790, broken off because ‘the symptoms of the approaching Revolution were becoming so fearfully manifest’, Knight never left England. He married, and settled down to the life of a landed gentleman, with a specific interest in breeding cattle.
So far, so typical, but he occasionally visited his brother in London, in his house in Soho Square, where he was a neighbour of the great Sir Joseph Banks. The latter had asked Richard Payne Knight to recommend an expert in the Herefordshire area to fill in a questionnaire for the Board of Agriculture, and he suggested his younger brother. It was not, according to his daughter, until he met Banks and began to attend his conversazioni, that Knight realised that his own researches into agricultural and horticultural topics were producing results which ‘had escaped the scrutiny of other naturalists’. Many of his investigations were into the productivity of the apple and pear trees which were then such an important part of the local economy of his county: the gradual failure of grafts as a tree grew old, and the necessity of renewing orchards by growing from seed; the movement of sap in trees; and the importance of the cambium layer for their growth and health. From this came his experiment into the persistence of the downward growth of roots and the upward growth of shoots: he devised a water-powered machine (made with ‘no other assistance than that of an old carpenter, who was not remarkable for his intelligence’), which kept the growing seeds constantly turning over and over, and watched what happened.
This was one of the experiments which greatly impressed Sir Humphry Davy, who became a lifelong friend. One of the attractions of Downton was the fishing in the River Teme, which Davy immortalised in a section of his Salmonia, or, Days of Fly Fishing; in his will, he left Knight a signet ring with a fish on the seal. Another great scientist, but one with whose ideas Knight disagreed, was Erasmus Darwin. He observed to Banks, ‘Dr Darwin’s imagination is generally too strong for his judgment’ (à propos the forces that drove the sap through plants), and Banks responded: ‘I observe, however, that Dr Darwin, who mixes truth and falsehood, ingenuity and perversity of opinions, exactly in the manner we mix the ingredients of a punch, has gone beyond your speculation of a nervous system in plants, by suggesting that they may have a brain. I confess, also, that he does not follow up his assertion with half the force of reason which you adduce in support of yours.’
Knight’s approach, modest, unassuming and thorough, was, Banks thought, just what was needed for his newest project, the Horticultural Society of London. He wrote in March 1804, announcing the formation of the society, with details of the first two meetings: ‘You will see that I have taken the liberty of naming you as an original member.’ In January 1811, Knight was elected president, and held the post for the remainder of his life. He was awarded a gold medal by the society in 1814, and in 1836 they decided to introduce a new medal bearing his head (the earlier one had portrayed Banks), and proposed to present the first (struck in gold) to Knight himself, in recognition of his physiological researches. He agreed – but on the condition that ‘I be permitted to subscribe a sum equivalent to its cost, to be employed in liquidation of the debt of the Society [then going through a period of financial difficulty], but not upon any other conditions.’
Knight’s sense of humour comes through in this account: urging a correspondent to brevity in writing a paper, he says: ‘…short papers, like short sermons, are more agreeable to the members of the Royal Society, some of whom come there with a rather strong propensity to fall asleep’. Writing to his daughter during a visit to London on Horticultural Society business in 1826, he reports than in spite of his urging that the office of president ought ‘to be held by a person of higher rank and consequence than myself’, he has been re-elected. In the same letter, he mentions a collection of plants sent back from the north-west coast of America by a young collector called Douglas, who is proposing a march from the Pacific to the Atlantic coast: prophetically, he adds, ‘…if he escapes, he will soon perish in some other hardy enterprise or other. It is really lamentable that so fine a fellow should be sacrificed.’
This idyllic-sounding life was tragically transformed a year later, when Knight’s only son, then aged 32, was killed in a shooting accident on the estate. It seemed likely that he would have followed in his father’s footsteps as a naturalist, and he had already undertaken a voyage north towards the Arctic Circle. A heartfelt letter of sympathy from Davy, and a letter of Knight to a friend, are moving in the very restraint with which they deal with grief, and it seems clear that Knight, though resigned, never really recovered from this disaster. The last page of the memoir of his life contains, fittingly, a list of the apples, cherries and other fruit, peas, potatoes and cabbage ‘raised by Mr Knight, which he considered worth preserving’.