Himalayan Balsam
Impatiens Glandulifera – Lus na pléisce
Himalayan Balsam is a high impact invasive plant belonging to the family Balsaminaceae. Originally from the West and central Himalayas, it is widely established in Ireland and much of Europe. Balsam can form dense stands. It thrives in damp areas, and low light such as woodland and riverbanks. Himalayan Balsam is popular in gardens and was likely introduced as a garden plant in the 1800’s. It spread from there and is now prominent on many riverbanks.
Distribution
(National Biodiversity Data Centre, Ireland, Himalayan Balsam (Impatiens glandulifera), image, accessed 09 May 2022)
Himalayan Balsam (Impatiens glandulifera)
Classified as a high impact invasive species by the Irish National Biodiversity Centre. Third Schedule listed species under Regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011.
Established
Identification:
- Easily identified by its pink or purple helmet shaped flowers in racemes that are seen in June to October.
- Produces hanging green seed pods
- Perennial plant which can reach between 4-7 ft in height (up to 3m).
- It has a hollow stem which, nearer the base of the plant, can often have red roots extending from the stem down towards the ground.
- Dark green elliptic leaves with serrated edges that can grow from 6-15cm long.
Reproduction:
Reproduction of Himalayan Balsam occurs in the Summer. Insects pollinate the plants. Hanging seed pods are explosive and can throw seeds 6m away from parent plant. Each plant can release up to 2,500 seeds. These seeds can often reach water and be transported downstream to colonise river banks.
Impacts:
Himalayan Balsam produces large amounts of nectar and so attract pollinators away from native plants. Himalayan Balsam forms large stands along rivers which then die back in the winter leaving the ground bare and easily eroded and susceptible to flooding.
Treatment:
- Mechanical: Hand pulling, strimming or cutting is often the most effective. The plant can be pulled before flowering in June. Wearing gloves, the plant can be pulled from the roots and left in a pile in situ or incinerated. The plant can also be cut at the base.
- Chemical: Herbicidal control can also be used at a later stage by applying a glyphosate herbicide through foliar spraying in dense stands and weed wiping in mixed stands.
- Biological: Grazing by cattle and sheep is effective from April throughout the growing season in some situations. It should be continued until no new growth occurs. Grazing on riverbank habitats can however have negative impacts such as poaching of river banks and the removal of other native vegetation which may act as a buffer zone.
More photos:
