German name : schmalblättriges Weidenröschen
English name : fireweed
French name : Épilobe en épi
I’ve know this plant for many years. In the German middle range mountains of the Rhön is grows abundantly in forrest clearings and along railway tracks. It’s a typical pioneer plant. It’s English name “fireweed” relates to the feature of quickly invading free space left after a fire .
Recently I’ve seen it in Scotland (see pic taken near Balloch, along Loch Lomond), in the Midlands and Highlands – once even growing on the roof of a house!
Remarkable is not only its relatively tall growth (up to 250 cm  – even though from my observations somewhat less tall plants (around a good 150 cm I’d say) seem to be more common), its bright pink flowers that can be easily spotted from far (e.g. when hiking in the Scottish highlands) but also its fluffy seeds surrounded by silken hairs. They are a good example of wind-dispersed seeds that are easilly carried by the air and float weighlessly in the wind. I’ve seen them piling up on the ground in early autumn.
New to me was that the German botanist Christian Konrad Sprengel discovered the mechanism of cross-pollination on this species in 1790 . Worth exploring – was self-pollination already known as a principle at this time? How did he discover/prove it?
Individual flowers are arranged in the upper third of the stem and start flowering from the bottom to the top of the inflorescence. It is not uncommon to find both mature seeds that are being released from the plant and flowerbud on the same stem.