Have you seen invasive Himilayan Balsam growing near your local rivers and streams? If you’re not sure what you’re looking for, read on to learn how to identify this troublesome plant and help us control it around the River Thame catchment.

What does Himilayan Balsam look like? Himalayan Balsam is an annual herbaceous plant characterized by its rapid growth, often reaching heights of up to three meters. The plant features hollow, reddish stems that are smooth and hairless. Its leaves are lanceolate, with serrated edges, typically arranged in whorls of three around the stem. The leaves can grow up to 15 centimeters (6 inches) long. The plant's flowers are pink to purple, sometimes white, with a helmet-shaped upper petal that curves forward.

How did Himilayan Balsam get here? The plant is native to the Himalayas and was introduced to the UK in 1839 as an ornamental addition to gardens. However, it didn't take long for it to escape cultivation and spread rapidly along rivers, roadsides, and waste grounds. Himalayan Balsam has a unique way of dispersing its seeds—each plant can produce up to 800 seeds that are shot up to seven meters away when the seed pods explode upon touch. This explosive dispersal method makes containing its spread particularly challenging.

Why is Himilayan Balsam a problem? It outcompetes native plants by forming dense stands, which reduces habitat diversity and leads to a loss of biodiversity. During the winter, the plants die back, leaving riverbanks bare and vulnerable to erosion. This increased erosion causes sedimentation in rivers, adversely affecting water quality and aquatic life.

What have we been doing to help? Over the last few weeks, teams of volunteers have turned out to our Balsam Bashing Work Parties along the Bear Brook in Fairford Leys. Despite the thousands of plants growing alongside the brook, many hands make light work and the volunteers have cleared over 2.3 kilometers of invasive balsam! These efforts are part of a wider initiative launched by RTCT in late 2023 called Community Action for the Bear Brook. The aim of this project is to engage and empower local residents to play a pivitol role in improving the health of their local brook. Resident who have attended Balsam Bashing sessions have remarked "I never knew about this invasive plant but now that I know what it looks like, I will let you know where I see it and pull it out!”.

What can you do to help? Keep an eye out for Himilayan Balsam when walking alongside rivers and streams. If you spot some in the Thame catchment, email us at enquiries@riverthame.org at include:

• A photo of the plant(s)
• An exact What3Words location
• Submit your record to the INNS Map

If you’re a local resident in the Aylesbury area who wants to get involved in the Community Action for the Bear Brook Project, sign up on our volunteer platform and make sure to include “Community Action for the Bear Brook” on your sign-up form.

Sign up here

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Many thanks to the John Lewis Partnership Foundation for their generous funding towards the Community Action for the Bear Brook project.