Nature · Wildflowers & flowers

Rosebay willowherb

Flowers June to September

Chamaenerion angustifolium — Onagraceae

Rosebay willowherb is the tall magenta spike that colonises railway embankments, felled woodland, burnt ground and bomb sites. Scarce in Victorian Britain, it exploded across the country in the twentieth century, and the two names it earned — fireweed and bombweed — record why. Each plant can shed up to eighty thousand plumed seeds, and it is the county flower of London.

How to spot them

▸A tall spire, to about 1.5 m, of deep pink four-petalled flowers opening from the bottom up
▸Leaves lance-shaped and arranged in a spiral up the unbranched stem, willow-like with a pale midrib
▸Long, narrow, upward-pointing seed pods that split into four to release cottony plumes
▸Style curving down below the four stamens; the flowers are slightly unequal, not radially symmetrical
▸Disturbed ground: railway banks, clearings, burnt or bulldozed land, road verges, June to September

How to know it

A tall magenta spire opening from the bottom up, with lance-shaped leaves spiralling up an unbranched stem

Rosebay willowherb — Chamaenerion angustifolium.

Known as bombweed in the south east after it colonised the ruins left by the Blitz

Rosebay willowherb.

Also called fireweed, because it germinates in the heat of bonfires and burnt ground

Rosebay willowherb — the floral emblem of Yukon under that name.

Each plant can release up to eighty thousand seeds, every one with a cottony parachute

Rosebay willowherb, according to the Wildlife Trusts.

A scarce plant in Victorian Britain that spread nationwide in the 20th century along railways and felled woodland

Rosebay willowherb.

County flower of London; its four petals are unequal and its style curves down beneath the stamens

Rosebay willowherb.

An evening-primrose relative whose old genus name, Epilobium, means 'upon a pod'

Rosebay willowherb — family Onagraceae; now Chamaenerion angustifolium.

Quick-fire facts

•Family Onagraceae, with the evening primroses and fuchsias; Chamaenerion angustifolium, also written Chamerion angustifolium and formerly Epilobium angustifolium
•angustifolium means narrow-leaved
•The Wildlife Trusts note it grows to 1.5 m and that a plant may produce up to 80,000 wind-borne seeds
•County flower of London in Plantlife's 2002 County Flowers survey
•Called fireweed in North America, where it is the floral emblem of Yukon; bombweed in wartime Britain
•Epilobium, its old genus, means 'upon a pod', because the flower sits on top of the long ovary
•A pioneer of disturbed ground: wartime felling, burning and bombing gave it the bare, ash-rich ground it needs
•Young shoots have been eaten as a vegetable, and in Russia the fermented leaves make a tea known as kapoor or Ivan chai

Drill it — 8 cards

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Sources

The Wildlife Trusts — Rosebay willowherb