Best time to see: Jun to Aug

Key facts

Tall, red-purple whorled spikes in late summer

In damp places, and especially by rivers and streams

An invasive plant in parts of North America

Extras

Plant 1–2.5m tall, softly downy, upright; flowers on spikes at the top

Purple flowers with five or six narrow petals

Leaves pointed, in opposite pairs on the lower stem