When looking at an overview of Himalayan balsam, it is worth knowing that Himalayan balsam is the largest annual species in the UK, which can grow up to 8 feet in a single season. It can spread quickly and cause many problems for the local ecosystem. It is originated from the foothills of the Indian and Pakistani Himalayas and can dominate native plants for resources, light, and space.
It is commonly found alongside streams, riverbanks or around lakes and ponds, in ditches, wet woodlands, and damp meadows. Himalayan balsam can tolerate low levels of light and also shade out other plants, thus slowly impoverishing the habitats and killing off other vegetation. Sometimes, it is seen in many gardens, either grown deliberately or uninvited, but care should be taken to make sure that it doesn’t escape into the wild.
How does the Himalayan Balsam tree spread its seeds?
On average, Himalayan balsam can produce up to 2500 seeds each plant. Those seeds will be explosively released from capsules during the distribution. The seeds will be viable for up to 1.5 years and are readily spread in water, by wind or human activities. In many cases, the seeds can be spread up to 23 feet from the mother plants. Many seeds can drop into the lake or pond and contaminate riverbanks downstream or land, but the explosive property of its seed release indicates that it would also spread upstream.
The aggressive dispersal of seed, along with the high production of nectarine that attracts pollinators, usually enables the Himalayan Balsam to outperform the native plants. Also, this species promotes the erosion around river bank areas because of its death in the winter, which leaves the bank uncovered from flooding. Invasive Himalayan balsam also has an adverse impact on indigenous plants by attracting pollinators like insects. Under the Weed Control Act, it is regarded as a “prohibited poisonous weed.”
The invasion of Himalayan balsam
The plant was first brought to the UK in 1839 at the same time as Japanese knotweed and giant hogweed. All of them were promoted as being herculean and splendidly invasive to rival the expensive growth of orchids in the greenhouses. However, within 10 years, Himalayan balsam started to spread along the ecosystem of England.
These days, it has appeared across almost all of the UK and many local wildlife trusts even organise some events to control it. However, such efforts might do more harm than good in some circumstances. Removing the riparian stands of the plant might open up more space for other aggressive invasive species like Japanese knotweed and help with seed spreading. Many studies also show that Himalayan balsam might expose allelopathy, which can excrete toxins and have an adverse effect on the neighbouring plants. As a result, it has a competitive advantage in the ecosystem, so when considering Himalayan balsam removal, make sure you look into all of the related impacts.