1/2 idea No. 6: Weed theory

(I am sharing my possible research ideas, see my tweet here. Most of them remain only 1/2 or 1/4 ideas, so if any of them seem particularly promising or interesting let me know @jon_agar or jonathan.agar@ucl.ac.uk!)

As well as being a historian of science and technology I am a keen amateur botanist, and the two can overlap.

There’s no need to go to the countryside to find nature. Cities are full of wild plants. Each plant species has a history. They can therefore be primary sources for understanding the urban past, so long as the skills are learned to answer the key question: what’s that plant?

In my third-year undergraduate course, Nature, Technology and the Environment, I run an exercise that, I have found, at first bemuses students, then provokes them, and then, when they get it, is often the best teaching experience ever.

I ask them to bring in a weed to class.

I then identify the plant (introducing the basics of classification and taxonomy), and draw out lessons, biological and historical.

For example, Shepherd’s-purse (Capsella bursa-pastoris) is an ‘archaeophyte’, probably arrived with Neolithic farming, but also has a very long-lived seed bank, adapted well for cracks in city pavements. Likewise, annual meadow-grass (Poa annua), a native plant, flowers all year round, exploiting urban niches. Oxford ragwort (Senecio squalidus), a native of Mount Etna, escaped from Oxford botanical garden in the 1790s, a voyage that parallels, not coincidentally, the 18th century Grand Tour. Shaggy-soldier (Galinsoga quadriradiata, from Mexico), Buddleja davidii (from China), and Conzya canadensis Canadian (native of North America) tell stories of global trade.

UCL was once one of the world centres of botanical education. The life sciences have long since moved away from natural history. Today science students might intensively study one species, the Thale cress Arabidopsis thaliana, a model organism for plant science, but would be highly unlikely to have been taught field identification of other plants. My minor revival of botanical identification at UCL therefore makes another connection to understanding the past.

But what is this to do with weed theory?

Weeds are good to think with. Weeds are plants in the wrong of place. Just as Mary Douglas showed we could think deeply about ‘dirt’ as matter out of place, so weeds can tell us about how we categorise the spaces and kinds around us. Weeds are category transgressors, and by doing so reveal the categories’ existence. One of our best nature writers, Richard Mabey, argued that ‘how and why and where we classify plants as undesirable is part of our ceaseless attempts to draw boundaries between nature and culture, wildness and domestication’. There is a philosophy here.

I am also deeply interested in the ways that nature and technology intersect. City weeds are part of, and a response to, an urban environment formed by technological systems of transport and building. They exploit artificial niches. They are also subject to our chemical technologies, and evolve accordingly – one of the plants my class learn to recognise, Groundsel (Senecio vulgaris), became herbicide-resistant, apparently the first of its kind, by 1990. The distribution map (illustrated) of Danish scurvy-grass – originally a seaside plant, which received its name from its antiscorbutic properties – now traces out the UK road system, because of winter salting.

But weeds are not part of the technological system even as they trace it. Other plants (think of arable crops) certainly are – modern agriculture is a machine for moving biological material from seed to plate.

One of the first steps I have taken in thinking about this subject is, very broadly, to classify the ways that nature and technology intersect. I proposed eight types (of which weeds appear in Type 4, ‘Environment as something alongside an artificial world’), in my paper that appeared in an collection, edited by myself and Jacob Ward, Histories of Technology, the Environment and Modern Britain, open access from UCL Press, 2018)

I am now thinking about what to do next with this topic.