Species guide
Japanese knotweed
Nuisance, not harmfulReynoutria japonica
How to recognise it
Bamboo-like hollow stems speckled purple, growing in a zigzag, with shovel- or heart-shaped leaves and sprays of creamy-white flowers in late summer.
Is it dangerous?
Not toxic, but an extremely aggressive invasive that can damage foundations, drains and paving. In some places (e.g. the UK) it's legally controlled and can affect property sales.
What to do
Don't dig or strim it — fragments regrow and spreading it can be an offence in some regions. Use specialist removal and check local rules.
Recorded 504,184 times in the wild worldwide.
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