Himalayan balsam Impatiens glandulifera
|Best Time to See||July, August, September, October|
A non-native invasive plant.
The largest annual plant in Britain, growing up to 2.5m high from seed in a single season. Himalayan balsam spreads quickly as it can project its seeds up to four metres. Many seeds drop into the water and contaminate land and riverbanks downstream, but the explosive nature of its seed release means it can spread upstream too.
It has large 'policeman's helmet' pink-purple flowers. Leaves have small red teeth at the edge and are in whorls of 3 or opposite. The stem is reddish.
Commonly found along riverbanks and streams, around ponds and lakes, in wet woodlands and in ditches and damp meadows.
What's the problem?
It spreads quickly and forms dense thickets, altering the ecological balance and character of wetland habitats. Many seeds drop into the water and contaminate land and riverbanks downstream, but the explosive nature of its seed release (seeds can be projected up to four meters away) means it can spread upstream too. It produces a lot of pollen over a prolonged season and is attractive to pollinating insects. There is concern that its presence may therefore result in decreased pollination for other native plants.
This species is listed on Schedule 9 of the Wildlife and Countryside Act in England and Wales therefore, it is also an offence to plant or otherwise cause to grow these species in the wild.
Removing Himalayan balsam
Indian balsam needs dealing with before it sets seed. If control is undertaken early enough to prevent flowering (and if this is achieved before seed has set) then eradication is possible in two or three years. We recommend that the plants, which are shallow-rooted, should be pulled out and disposed of by composting carefully, or by burning if seeds are present. If this is done on a regular basis and the plant is not allowed to set seed, it will eventually die out. Regular strimming of larger areas is also an option, as long as it is done often enough to prevent flowering.
Did you know?
Introduced in 1839, it was first cultivated as a greenhouse annual by gardeners.
Local names include Nuns and Jumping Jack, as well as Policeman's Helmet, Bobby Tops and Gnome's Hatstand which refer to the fact that the flower is decidedly hat-shaped. Himalayan Balsam and Kiss-me-on-the-mountain arise from the fact that the plant originates in the Himalayan mountains.
The genus name Impatiens, means "impatient", and refers to its method of seed dispersal. The species name glandulifera comes from the Latin words glandis meaning 'gland', and ferre meaning 'to bear', referring to plant bearing glands.
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