[127] Epilobium hirsutum, Great Willowherb
Introduction
Epilobium hirsutum, Great Willowherb, is a common wildflower or weed with lots of pink flowers.
It is also known as Hairy Willowherb or Great Hairy Willowherb.
There are about two hundred species of Epilobium, mostly called willowherbs.
In the UK, the closely related Chamaenerion augustifolium, is generally known as Rosebay Willowherb. (This is the only Chamaenerion species, which used to be considered to be Epilobium.)
Taxonomy
Kingdom – Plants
Division – Vascular Plants
Class – Angiosperms (Flowering Plants)
Order – Myrtales
Family – Onagraceae
Subfamily – Onagroideae
Tribe – Epilobieae
Genus – Epilobium
Section – Epilobium
Scientific Name – Epilobium hirsutum
Name
Willowherb comes from the similarity of the leaves to [307] Willow. Epilobium comes from Latinized Greek roots epi-lobos, ‘above toe lobe,’ relating to the position of the flower petals above the ovary. Hirsutum means hairy.
Chamaenerion originally meant ‘resembling Nerion’ in reference to what is now called Oleander, Nerium oleander. Linnaeus preferred Epilobium because of the awkward construction and spelling of Chamaenerion (now sometimes spelled as Chamerion.) The relationship of the two species is disputed. Augustifolium means narrow-leaved, which takes us back to Willowherb. Rosebay Willowherb adds references to the flowers resembling wild roses and the leaves resembling Bay.
Description
Epilobium hirsutum is a tall perennial plant, growing to about two metres in height.
The stems are covered with soft hairs.
The flowers are purple-pink, with four notched petals and a white stigma.
Habitat
Epilobium hirsutum is native to most of Europe, North Africa and parts of Asia – including all of the UK except North-western Scotland. It typically grows in wet areas. The large clump of plants shown below are beside a local lake.
See also
Chamaenerion augustifolium is known in North America as Fireweed but in the UK, it is always Rosebay Willowherb. It is native throughout the temperate Northern Hemisphere.
Whether Chamaenerion is actually a separate genus from Epilobium is still disputed and it is also sometimes argued that it should be called Chamerion. So, Rosebay Willowherb has the synonyms Epilobium augustifolium and Chamerion augustifolium.
It is a pioneer species, frequently found in disturbed areas. In Britain its is often found beside railways and in America it is associated with burnt sites after fires. Hence the name Fireweed.
Sometimes you can’t beat Wikipedia, which says of this species, “The inflorescence is a symmetrical terminal raceme that blooms progressively from bottom to top producing a gracefully tapered shape.”
It is particularly impressive when several grow together and reach the skyline.
The Species of Britain 