Rhododendron ponticum in Britain and Ireland: Social, economic and ecological factors in its successful invasion

Rhododendron ponticum is the most expensive alien plant conservation problem in Britain and Ireland. It was introduced in the eighteenth century, probably in 1763 from Spain, and was then described as a not fully hardy plant. It was expensive to buy. It was made hardier by artificial and natural selection and by hybridisation with Appalachian and other Rhododendron species. It is easy to propagate and became cheap and popular in the mid and late nineteenth century as an ornamental, for game cover and as a root stock for other ornamental rhododendrons. The lowest price was in about 1880 by which time it had escaped widely. The escapes were ignored by botanical recorders for over 50 years. It was scarcely recognised as a problem until between the two world wars. Major control projects date from the second half of the twentieth century.