Himalayan balsam

Himalayan balsam

(Impatiens glandulifera)

This annual plant grows to 3 metres high and is spread exclusively by seed. The seed pods explode when mature, scattering the small seeds up to 7 metres from the parent plant. The plants grow in dense stands along the banks of rivers and effectively suppress any native grasses and herbaceous plants. The balsam dies back in autumn, exposing the now bare bank-sides to erosive winter flows.