Best time to see: Jul to mid Oct

Key facts

A tall waterside annual with showy pink- or rose-coloured flowers in high summer, growing up to 2m high

Spreads its seed widely by means of explosive pods, which are then carried downstream

A good nectar plant, especially for bees, but forms dense stands on river banks that excludes all other plants

Extras

Plant often grows 1–3m high, making large patches; stout fleshy stems, often red

Flowers large; pale pink with white streaks to purple-pink

Leaves are long oval, pointed; in whorls