Best time to see: Jul to Aug

Key facts

Handsome yellow spikes of late summer, growing in wet places by fresh water such as stream banks

Secretes an oil which is collected by the few insects that visit (and pollinate) the plant to waterproof their nests

Only found in a few sites in Essex, including Essex Wildlife Trust reserve Cranham Marsh and Wanstead Park

Extras

Fairly tall downy perennial, with short-stalked leaves in whorls of 2-4 and flowers in branched clusters

Not to be confused with the garden plant often called the same, but really dotted loosestrife from south-east Europe