This paper examines the interplay of science and globalization through nineteenth-century British plant specimen exchange, focusing on the herbarium of the Royal Botanic Gardens, Kew. Applying social network analysis as an exploratory lens illuminates the overlooked contributions of local collectors, labourers, and intermediaries in the transcontinental movement of plants and knowledge.

Central to imperial science, the Kew Herbarium housed plant specimens acquired through colonial networks, representing complex relationships and power dynamics. Yet historical narratives often privilege figures like William Hooker, his son Joseph Hooker, and Joseph's son-in-law William Thiselton-Dyer, whose combined directorships from 1841 to 1905 marked a period of significant expansion and collecting activity at Kew. By decentering these figures, this study maps the broader networks of individuals and institutions underpinning botanical exchange. A focus on nineteenth-century Australian plant-collecting networks underscores the interdependence of these colonial actors, who both navigated and contributed to evolving nomenclatural and classificatory systems.

Combining archival research with social network analysis, the study explores mesoscale patterns of plant collecting, leveraging specimen label data to visualize connections between collectors. Network analysis thus provides a guided means of reading, and conversely, close reading informs the development of more nuanced and focused quantitative approaches in the history of science. Foregrounding the contributions of local collectors, horticulturalists, and other intermediaries, this research challenges the perception of Kew as the sole locus of British botanical progress and illustrates how the digitisation of scientific plant specimens yields a novel lens for surveying Kew's colonial archives.

The influx of plant specimens collected on voyages beginning in the fifteenth century through the colonial explorations of the nineteenth-century steamers spurred the study of live plants in European centers such as Paris, London, Copenhagen, Amsterdam, and Vienna. Greenhouses in India, the West Indies, and North American likewise were built to grow, study, and appreciate a wide diversity of temperate, tropical, desert, and alpine plants. Three themes emerge from contemplating the role of glass houses in history: 1. the embeddedness of conservatories in aristocratic culture; 2. the connections between greenhouses, colonialism, and the development of Western botanical science with greenhouses funded by the wealthy; and 3. the opening of these conservatories to the public. Each of these facets of the conservatory has informed what we know about climate and how we imagine it. Over the course of the upsets of political revolutions in America, France, and the West Indies, many of these greenhouses became open to the public. In this paper, I focus on the development of public access. How did this access impact the practice of botany? Did it change the kinds of plants collected or the way they were displayed? What was the connection between public greenhouses and the more modest versions of plants grown under glass in backyard greenhouses or on a window sill? How did visitors experience the heat and humidity in a tropical greenhouse and how did that inform their ideas about climate? The significance of botanical conservatories reached beyond their glass walls and ceilings.

The literature on Charles Darwin’s conversion to evolutionism essentially consists of two versions of the same causal hypothesis: he was supposedly converted by his discoveries and observations as a naturalist aboard HMS Beagle (1831-1836), either during the voyage itself or after consulting with experts upon his return. Currently, the post-voyage hypothesis is more widely accepted. This view is not only more credible than the traditional account of Darwin’s conversion in the Galápagos Islands, but it is also based on primary sources—the bedrock of modern historical research. However, it has notable flaws that call into question the reliability of these sources. For example, it does not convincingly explain why, among his contemporaries, only Darwin was converted by the evidence from the Beagle voyage. Despite these weaknesses, the post-Beagle conversion hypothesis has remained resistant to rejection because no credible and acceptable alternative could be proposed for a hypothesis derived directly from primary sources. Alistair Sponsel’s (2018) plausible revision of the early development of Darwin’s coral reef theory—the first theoretical breakthrough of the Beagle voyage—has put an end to this unsatisfactory status quo. A conversion hypothesis, modelled on the revised five-part early development of this theory and critically drawing on relevant primary sources, is not marred by the flaws that undermine the credibility of the post-Beagle conversion hypothesis. It shows that Darwin’s conversion involved more places and a bigger variety of experiences than hitherto thought.