In the early 1910s a young woman set out every day to walk the river banks near Galashiels in the Scottish Borders. Ida Hayward was recording something extraordinary: the arrival in the UK of hundreds of never-previously recorded plant species from all over the world. Hayward realised that seeds from these plants – including wildflowers, herbs, and grasses – had travelled thousands of miles attached to the fleeces of sheep, before being delivered to textile mills in bales of wool. She was one of the first to refer to these plants as ‘wool aliens’, a term which drew a direct connection between the movement of plants and people.
In 1919 Hayward published her observations in The Adventive Flora of Tweedside, co-written with another botanist, George Claridge Druce. Hayward listed 348 examples of ‘wool aliens’ discovered in Tweedside. More importantly, she also showed what these ‘extraordinary plant-occurrences’ revealed about ‘the mutual interdependence not only of individuals but of industries and communities’. By documenting how the ecology of a small patch of the Scottish Borders had been transformed by the textile industry Hayward drew attention to the environmental change caused by the global trade in wool.
Woollen and worsted production boomed in the 19th century, particularly in Scotland, West Yorkshire, and Wales. To feed this industry, Britain imported wool from around the world, principally from places that formed part of its vast imperial network, including New Zealand, Australia, and South Africa. Britain became the world’s largest importer of raw wool, and by the early 1920s around one third of the world’s sheep were located within the empire’s confines.
The majority of these sheep were merino. While they proved unsuited to the British climate, merino thrived in Australia, which became the wool powerhouse of the British Empire. The first merino sheep arrived in Botany Bay in 1797, only nine years after the first European settlement had been established there. Botany would soon become a byword for high-quality merino, and by the end of the 19th century over 100 million sheep roamed vast pastoral estates across Australia. While the cotton industry was underpinned by the plantation system, wool depended on the pastoral economy, which came to be associated with a different form of exploitation. Comparatively low in labour intensity, pastoralism required vast amounts of land for the grazing of sheep and cattle. In Australia the expansion of pastoralism by British settlers, together with sustained violence and harassment and the importation of diseases, drove Aboriginal people off their land.
Pastoralism also produced a wholesale transformation of the Australian landscape. Alongside the expansion of grasslands came the propagation of so-called ‘weeds’: imported plants unwanted by farmers and herders, but which nevertheless thrived in the newly expanded pastures. Thistles became a serious problem in Australia from the mid-19th century: these ‘vegetable plagues’, as one contemporary denounced them, became the subject of a national campaign of extermination in 1862. Knot grass, red sorrel (also called sheep’s sorrel), and dandelion also spread rapidly, suited as they were to the extensive pastures taking hold of the Australian landscape, and crowded out native species, reducing the quality of grassland so that it became unusable to farmers. The extension of grazing and the elimination of indigenous species such as kangaroo grass led to rapid soil erosion and the consequent degradation of pastures. As the quality of soils and pastures declined, the demand for land accelerated.
Many plant species travelled ‘accidentally’: as stowaways in cargo, luggage, and goods. But they also arrived in seed shipments imported specifically to alter the landscape to better suit its new ovine inhabitants. The ‘improvement’ of grasslands promised a scientific solution for boosting agricultural productivity. In New Zealand grass replaced acre upon acre of indigenous bush forest, wetland, and tussock grassland from the mid-19th century. Sheep, many of them merino crossbreeds, roamed these new grasslands, which were often planted with imported ‘English’ seed mixtures. As in Australia, newcomers such as dock, watercress, and white clover flourished in the new pastoral environments at the expense of indigenous flora. Similar processes altered the ecology of South Africa, the Falklands/Malvinas, and Argentina.
The environmental effects of the wool trade did not stop at the sheep farm. Imported wool was usually washed and ‘scoured’, a process which removed dirt and impurities. This dislodged the seeds which resulted in the plants that Hayward recorded in Tweedside, but it also released large quantities of lanolin, the oily substance found in sheep’s coats. Soaps, acids, and other substances such as ammonia and bleach were used in these processes. All of this was flushed directly into streams and rivers. Wool was often dyed, a process which used a medley of additional chemical pollutants. The pollution caused by the dyeing industry was intensified with the arrival of coal-based aniline dyes in the mid-19th century, which produced a greater variety of bright colours, but were much more toxic than organic dyes.
Wool manufacturing posed such a threat to the health of British rivers that an 1871 report by the Rivers Pollution Commission focused its attention on woollen mills and associated businesses across England and Scotland, highlighting the foul state of rivers and streams. By far the worst offender was Bradford Beck, which the commissioners described as a ‘black, filthy, and offensive stream’. The author of one memorandum sent a stark message about the state of pollution by dipping his pen not in ink, but in water drawn from the River Calder.
Most of the species that Ida Hayward discovered during her walks did not become naturalised in the UK. As wool scouring and washing began to employ more intensive methods and chemicals, the number of ‘wool aliens’ capable of germinating after the production process fell. A few species, however, had already established themselves. One of the plants that Hayward identified, the pirri-pirri burr, originated in New Zealand and Australia and was almost certainly introduced by the wool trade. Today, it continues to thrive across much of the UK and Ireland. The British wool industry has long since lost the dominance it once enjoyed, but evidence of its environmental effects lives on in pastures, fields, and rivers in Britain and around the world.
Max Long is Research Fellow in History at Jesus College, Cambridge.