Way back before you were born, in 1985, my university archaeology tutor handed our study group a cardboard box full of Roman pottery sherds and asked us to sort them into groups. When we asked how he would like them sorting, he explained that working that out was the whole point of the exercise.
There are at least as many ways of categorising things as there are people to categorise them. But some ways of categorising seem more sensible and useful than others. When it came to Roman pottery, colour, we soon decided, was not a particularly useful way of categorising sherds (an observation which won nodding approval from our colour-blind tutor), but the impurities and inclusions (or lack of them) within the sherds quickly helped us to sort them into what seemed—to our untrained eyes at least—to be sensible groups: flawless samian ware, versus groggy iron age stoneware, for example.
Like Roman pottery, living species can be categorised in many different ways—some of them more useful than others. Debates about such taxonomies can get rather heated, and I don't intend to get embroiled in them here. But, this week, I came across an intriguing and rather barmy plant taxonomy suggested by the Nineteenth Century art critic and social thinker John Ruskin. It is described in Richard Mabey's new book Weeds: How Vagabond Plants Gatecrashed Civilisation and Changed the Way We Think About Nature:
John Ruskin would have been appalled by this mechanical exploitation of a wild plant, and by the assumption that the burriness of burdock had evolved to help the plant distribute its seeds. In the first volume of his Proserpina - Studies of Wayside Flowers (1874) - he describes how the construction of a burdock's leaf (which he perfectly describes) contributes to its beauty:
When a leaf be spread wide, like the Burdock, it is supported by a framework of extending ribs like a Gothic roof. The supporting functions of these is geometrical; every one is constructed like girders of a bridge, or beams of a floor with all manner of science in the distribution of their substance in the section … But when the extending space of a leaf is to be enriched with the fullness of folds, and become beautiful in wrinkles, this may be done either by pure undulation as of a liquid current along the leaf edge, or by sharp `drawing'—or 'gathering' I believe ladies would call it—and stitching of the edges together. And this stitching together, if to be done very strongly, is done round a bit of stick, as a sail is reefed round a mast; and this bit of stick needs be compactly, not geometrically strong; its function is essentially that of starch,—not to hold the leaf up off the ground against gravity; but to stick the edges out, stiffly, in a crimped frill. And in a beautiful work of this kind, which we are meant to study, the stays of the leaf—or stay-bones—are finished off very sharply and exquisitely at the points; and indeed so much so, that they prick our fingers when we touch them; for they are not at all meant to be touched, but admired.
A few pages later, more bluntly, he urges readers to study its structure: 'Take a leaf of burdock—the principal business of that plant being clearly to grow leaves wherewith to adorn foregrounds.'
These are extraordinary and baffling passages, full of intimate glimpses of the engineering of leaves, but seeming to suggest that these exist more for the beatification of the observer than the livelihood of the plant. Proserpina is like this throughout. It is a confused and at times deranged attempt to devise a new, anti-Linnaean plant taxonomy, based on aesthetic principles rather than scientific understanding. It passes moral judgements on whole orders of plants, yet sometimes has moments of startlingly original observation and insight, as in this evocation of a poppy flower: 'We usually think of the poppy as a coarse flower; but it is the most transparent and delicate of all the blossoms of the field … the poppy is painted glass; it never glows so brightly as when the sun shines through it. Wherever it is seen—against the light or with the light—always, it is a flame, and warms the wind like a blown ruby.' This may be the best descriptive passage on the poppy in the English language, and it comes close to offering a poetic intimation of the role of the sun in plant growth, and of the seductive power of the hot scarlet petals to other creatures.
But such plant- or nature-centred views were an abomination to Ruskin. In one of his deeper depressions he remarked with disgust that the theory of photosynthesis made us look on leaves as no more than 'gasometers'. Beauty of form or function in a plant he saw as an abstract quality, planted there by God for the elevation of humans. That it might in some way be 'recognised' by a non-human organism was repugnant to him. That the ruby flame of a poppy, or the intricate anatomy of an orchid bloom, might be attractive—be beautiful, as it were—to an insect was a blasphemy. This led Ruskin to believe in a hierarchy of organisms based on his own aesthetic ideas. 'The perception of beauty,' he wrote, land the power of defining physical character, are based on moral instinct, and on the power of defining animal or human character. Nor is it possible to say that one flower is more highly developed, or one animal of a higher order, than another, without the assumption of a divine law of perfection to which the one conforms more than the other.'
Ruskin had in effect devised an aesthetic version of the Doctrine of Signatures. God had 'signed' certain plants with imprimaturs—symmetry of petals, for instance, or the angles between stalk and leaf—which might have some base biological function, but which were principally indices of the divine quality of beauty. It was the responsibility of the cognoscenti to recognise and interpret these signs…
Ruskin didn't deny that the forms of plants could be functional. But he passionately denied that they had any significance or value (beyond the purely mechanical) inside the universe of their own lives. A quality like beauty has no connection with the grace and elegance with which a plant lived out its existence on its own terms and amongst its own kind. It could only be granted to them, or withheld, by human beings with the divinely endowed gift of making moral judgements on nature. Which is why he argued that the flower itself was the be-all and end-all of plant existence, not because it was an inspiration to insects and the forerunner of the seed, but because of the pleasure that it gave to human eyes.
I'm all for people deriving aesthetic pleasure from plants, but, it seems to me, you can take such pleasures too far.