The last word goes to the Oxford Ragwort (Senecio squalidus). This plant was introduced to the Botanic Garden from Sicily in 1794. Safely confined behind the high walls of the garden for many years, it escaped in the nineteenth century to establish itself in the cinders of Oxford's railway, the clinker being similar in quality to its native volcanic soil in Sicily. Having spread along the railway system during its expansion in Victorian times, the plant is now common throughout southern England.