Country and coast: Fireweed and the many other names of a flower on the rise

IT isn't just heather that turns our landscapes purple in July and August. Rosebay willowherb was once so rare, that in the late 1800s, Yorkshire Naturalists' Union made a special excursion to Thorne Moors to see this remarkable and at that time, uncommon flower.

Rosebay goes by various names from Chamerion angustifolium (or formerly for older botanists Epilobium), to fireweed, railway flower, bombweed, and even ranting widow.

Across Britain, from being a scarce flower in remote moors, uplands and woodlands, it underwent a huge transformation to colonise swathes of countryside and urban greenspace too.

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Various explanations have been proposed for this; perhaps different subspecies, native and non-native, or even a hybrid between the smaller and more delicate native variety and a bigger brasher North American cousin. This had what we call "hybrid vigour" and went on to rampage across suitable habitats wherever it could.

Much of this is conjecture but what we do know was that the advance was triggered by key human environmental impacts.

Initially the great linear route-ways of firstly the canals and then the railways, opened up easy conduits for movement across the county and penetrated deep into Yorkshire's towns and cities. For a plant with super-abundant wind-blown seeds this was a great opportunity to spread and disturbance in these linear habitats encouraged this coloniser.

Frequent fires along railway lines due to sparks from steam engines were a vital key to this success – the names railway flower and fireweed tell their own story.

Then, during the First World War, vast areas of woodland were clear felled for the wartime effort and the disturbed ground, often with extensive burnt patches due to the firing of brash, was a golden opportunity.

In the urban areas of towns and cities there was another unwelcome helping hand for rosebay when towns and cities were badly blitzed, Sheffield being especially badly affected, and rosebay took hold.

The name bombweed follows this dramatic urban expansion or perhaps explosion. But all the while the flower has gone from strength to strength. It undoubtedly gained from the 1950s planners' efforts to remodel towns, and from downturns in industry with widespread 1970s and 1980s dereliction.

Now it is a splendid sight along many long-distance footpaths on old railway lines.

Professor Ian D Rotherham is a researcher, writer and broadcaster on wildlife and environmental issues and can be contacted on [email protected] ukeconet.co.uk or via the Editor.