In 1839, Britain imported Himalayan balsam to Kew Gardens as a showy garden flower: 187 years later, the escaped invader weakens UK riverbanks every winter

A charming Victorian garden plant, Himalayan balsam, is now a serious threat to British riverbanks. Its rapid summer growth outcompetes native vegetation, leading to the death of deep, stabilizing root systems. When the balsam dies back in winter, the weakened banks, lacking natural reinforcement, are left vulnerable to significant erosion, impacting river ecosystems and water quality.