Himalayan Balsam is a native of the Himalayas but has been spread across most of the Northern Hemisphere due to human introduction. It is so effective at spreading that it is considered among the most invasive species of plants.
It typically grows between 1 to 2m tall with a green or red tinged stem and long lanceolate leaves up to 23cm. The flowers are pink roughly 3cm tall, 2cm wide with a hooded shape. After flowering the plant produces seed pods that explode when disturbed. This helps spread the seeds as they can be fired 7m from the plant.
Some research also suggests that Himalayan Balsam may exhibit allelopathy which is the release of chemicals into the environment that inhibit competition from other species. The plant also contributes to damage to river banks as it outcompetes native plants during the summer then completely dies away in the winter leaving the river banks bare. This leads to higher levels of erosion.
The plant was rated as producing the largest amount of nectar per flower in the UK Insect Pollinators Initiative survey. This is great news for pollinators but it is thought it may cause the same pollinators to overlook native plants producing a negative effect on them.