Plant Hybridity Before Mendelism: Diversity and Debate in British Botany, 1837-1899

This thesis offers a new account of why plant hybridity was controversial in Victorian Britain. Against the received historiography, which depicts a generalised, religiously motivated opposition among botanists to the idea of natural plant hybrids, and treats hybridising—the artificial sexual crossing of species—as a practice used only by horticulturalists and plant breeders, the thesis draws a complex map of interacting but distinctive botanical communities that were all involved in using hybridising to contribute to science. At the centre of the thesis are three episodes focusing on plants—oxlips, willows, and ferns—which employ an object-orientated historiography to highlight for the first time how the transfer of hybridising between these diverse plant knowledge communities eroded earlier attempts to demark socially the science of ‘botany’ from horticulture and plant breeding. Religion featured in these controversies, but in complex and sometimes surprising ways; in the 1840s, religiously motivated practitioners appealed to hybridisation as a conservative alternative to radical Lamarckian transmutation. After 1859, the botanical practices of a new Darwinian biology included hybridising, which impacted the paper practice of plant taxonomy in relation to hybridity. Local botanist-cultivators used their ‘special knowledge’ of hybridity to become authoritative taxonomists. Corroboration and collaboration between plant knowledge communities in the closing decades of the century is a corrective to standard histories which emphasise a growing distance between natural history and biologist communities after 1890. Finally, the oft-cited notion of widespread religious hostility to plant hybridity was itself a product of this long history of controversy, originating in the hagiographic historiography launched at the Royal Horticultural Society’s 1899 Hybridization Conference. Overall, the thesis reveals a hidden biography of the practice of plant hybridising in Victorian botanical science and how it connected knowledge-making among farmers, gardeners and local botanists with philosophical and academic practitioners, producing diversity and debate.