Impatiens glandulifera (Himalayan Balsam )
Himalayan Balsam
Background
Himalayan balsam is an annual herb, native to the western Himalayas. In the early 1800s it was introduced to many parts of Europe, New Zealand and North America as a garden ornamental. Himalayan Balsam has an orchid shaped flower resembling a British policeman’s helmet, which gave rise to its other common name of “Policeman’s helmet”.
Himalayan balsam can completely cover an area and crowd out native vegetation. Mature seed capsules explode when touched and can eject seeds as much as 5 metres from the parent plant, giving it the alternate common name of “Touch-Me-Not plant”. It is mostly found in riparian areas, especially river edges and wetlands.
Range
Since its introduction to parts of North America, Europe and New Zealand, himalayan balsam has been successful in escaping cultivation and invading natural areas. In Canada, it has been reported in eight provinces including British Columbia, Manitoba, Ontario, Quebec, Nova Scotia, New Brunswick, Prince Edward Island and Newfoundland. It is also naturalized in the United States.
Impacts of Himalayan Balsam
Creates dense stands that prevent native plants from establishing and reduce biodiversity and ecological value of land. Prolific nectar producer, drawing pollinators away from surrounding native species. Produces about 800 seeds per plant, which are released from capsules once they are disturbed or dry out. An annual species that can aggressively replace native perennial plants along river banks, leading to soil erosion.
How to Identify Himalayan Balsam
Stems are hollow and smooth with purple to reddish colour. Able to grow 1 to 3 metres tall.
Leaves are 6-15 centimetres long and are widest in the middle with sharply toothed edges.
Flowers have 5 pink, white or purple petals, with 5-10 flowers on each stem.
Seeds are produced in capsules 1.5-3.5 centimetres long with up to 16 seeds inside. Mature seed capsules explode when touched, launching seeds in all directions up to 5 metres away.
Looks similar to Ontario’s native Jewelweed (Impatiens capensis), which is a related species with yellow-orange flowers.
What You Can Do
Learn how to properly identify Himalayan balsam and how to prevent accidentally spreading this invasive species.
Avoid using invasive plants in gardens and landscaping.
Buy native or non-invasive plants from reputable garden suppliers. See Grow Me Instead: Beautiful Non-Invasive Plants for Your Garden.
Learn how to effectively manage himalayan balsam on your property. Do not dispose of invasive plants in the compost pile – discard them in the regular garbage.
When hiking, reduce the spread of invasive plants and seeds by staying on trails and keeping pets on a leash.
If you find himalayan balsam or other invasive species in the wild, please contact the Invading Species Hotline at 1-800-563-7711, or visit EDDmapS Ontario to report a sighting.
www.invadingspecies.com
Impatiens glandulifera
Invasive species
Himalayan Balsam is sometimes cultivated for its flowers. It is now widely established in other parts of the world (such as the British Isles and North America), in some cases becoming an invasive species weed. The aggressive seed dispersal, coupled with high nectar production which attracts pollinators, often allows the Himalayan Balsam to outcompete native plants. Himalayan Balsam also promotes river bank erosion due to the plant dying back over winter, leaving the bank unprotected from flooding. Invasive Himalayan Balsam can also adversely affect indigenous species by attracting pollinators (e.g. insects) at the expense of indigenous species. It is considered a "prohibited noxious weed" under the Alberta Weed Control Act 2010.
In the UK the plant was first introduced in 1839 at the same time as Giant Hogweed and Japanese Knotweed. These plants were all promoted at the time as having the virtues of "herculean proportions" and "splendid invasiveness" which meant that ordinary people could buy them for the cost of a packet of seeds to rival the expensive orchids grown in the greenhouses of the rich. Within ten years, however, Himalayan balsam had escaped from the confines of cultivation and begun to spread along the river systems of England. Today it has spread across most of the UK and some local wildlife trusts organise "balsam bashing" events to help control the plant. However, a recent study (Hejda & Pyšek, 2006) concludes that in some circumstances, such efforts may cause more harm than good. Destroying riparian stands of Himalayan Balsam can open up the habitat for more aggressive invasive plants such as Japanese knotweed and aid in seed dispersal (by dropped seeds sticking to shoes). Riparian habitat is suboptimal for I. glandulifera, and spring or autumn flooding destroys seeds and plants. The research suggests that the optimal way to control the spread of riparian Himalayan Balsam is to decrease eutrophication, thereby permitting the better-adapted local vegetation that gets outgrown by the balsam on watercourses with high nutrient load to rebound naturally. They caution that these conclusions do probably not hold true for stands of the plant at forest edges and meadow habitats, where manual destruction is still the best approach.
The Bionic Control of Invasive Weeds in Wiesbaden, Germany, is trying to establish a self-sufficient project to conserve their local biodiversity by developing several food products made from the Impatiens flowers. Eventually, if all goes well, this project will have the Himalayan Balsam financing its own eradication.
In August 2014, CABI released a rust fungus in Berkshire, Cornwall and Middlesex in the United Kingdom as part of field trials into the biological control of Himalayan Balsam.
Some research also suggests that I. glandulifera may exhibit allelopathy, in which it excretes toxins that negatively affect neighboring plants, thus increasing its competitive advantage. This would further support the conclusion that pulling or cutting the plant and leaving it to decompose is not the best method to control this invasive species.
The Royal Horticultural Society and the Centre for Ecology and Hydrology recommend that pulling and cutting is the main method of non-chemical control, and usually the most appropriate. Natural Resources Wales has used manual methods such as pulling plants and using strimmers to largely eradicate Himalayan Balsam from reaches of the River Ystwyth.
en.wikipedia.org
