Scientific name: Impatiens glandulifera
AKA: Policeman’s Helmet, Indian Balsam, Jac y Neidiwr (Welsh)
Native to: West and central Himalayas
Habitat: Found mostly on river banks and in damp woodland, can grow in other damp habitat
A tall, attractive, annual herb related to busy Lizzie, with explosive seed heads. Although easy to identify as a mature plant with its pink-purple flowers, fleshy stem and characteristic leaves, the seedlings and last year’s dead stems of this annual are more difficult to spot.
Introduced as a garden plant in the early 19th century and first recorded in the wild in 1855. Often favoured by the general public for its aesthetic appeal and is still deliberately planted on occasion. Now widespread in the UK, especially along urban rivers.
Spreads solely by seeds, which are small and easily carried by wind or water. Out-competes native species in ecologically sensitive areas, particularly river banks. Where it grows in dense stands along river banks it can impede flow at times of high rainfall, increasing the likelihood of flooding. Die back of extensive stands over winter can leave river banks bare and exposed to erosion.
Himalayan balsam is listed under Schedule 9 to the Wildlife and Countryside Act 1981 with respect to England and Wales. As such, it is an offence to plant or otherwise allow this species to grow in the wild. The transportation of seeds or whole plants is also an offence under the Invasive Alien Species (Enforcement and Permitting) Order 2019 in England and Wales and Section 14AA of the Wildlife and Countryside Act in Scotland. This means that no seeds or plants should be removed from the site where they currently grow, and sowing seeds or planting elsewhere either deliberately or accidentally would be a particularly serious offence.
Sampling on our stretch of the river Severn in 2012 identified Himalayan balsam in the locations marked by blue dots, below.