Himalayan Balsam - Impatiens glandulifera
We have an invasion of this alien plant on our river banks so we would ask members of the ATAA to assist us by pulling these plants up whilst fishing, before they produce seed pods.
Each plant can produce up to 800 seeds. These are dispersed widely as the ripe seedpods shoot their seeds up to 7m (22ft) away.
Once established in the catchment of a river the seeds, which can remain viable for two years, are transported further afield by water.
Himalayan (or Indian) Balsam is an annual herb that germinates from seed in February/March and dies back each winter.
The stems are reddish and the plant grows to between 1 and 2m tall. The long lance-shaped leaves with toothed edges are arranged in pairs, or three to node and are mid to dark-green.
The purplish-pink flowers which appear in July-September are large and distinctive.
Himalayan Balsam prefers to grow in wet ground so is often found along river banks and smaller watercourses and in damp hollows in woodland.
Amongst the problems this plant causes are:
Shading out native plants.
Competing for pollinators – bees prefer it to most other plants, which therefore produce less seeds.
Erosion - Himalayan Balsam dies back in winter leaving bare areas vulnerable to erosion by rain, high water etc, and the plants it shades out (grasses etc) have roots that would bind the soil preventing erosion.