| Himalayan Balsam Impatiens glandulifera |
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|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Ericales |
| Family: | Balsaminaceae |
| Genus: | Impatiens |
| Species: | I. glandulifera |
| Binomial name | |
| Impatiens glandulifera Royle |
|
Impatiens glandulifera is a large annual plant native to the Himalayas. Via human introduction it is now extant across much of the Northern Hemisphere.
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The common names Policeman's Helmet, Bobby Tops, Copper Tops, and Gnome's Hatstand all originate from the flowers being decidedly hat-shaped. Himalayan Balsam and Kiss-me-on-the-mountain arise from the fact that the plant originates in the Himalayan mountains.
The species name glandulifera comes from the Latin words glandis meaning 'gland', and ferre meaning 'to bear', in that the plant has glands that produce a sticky, sweet-smelling, and edible nectar.
It typically grows to 1 to 2 m (3.3 to 6.5 ft) high, with a soft green or red-tinged stem, and lanceolate leaves 5 to 23 cm (2 to 9 in) long. The crushed foliage has a strong musty smell. The flowers are pink, with a hooded shape, 3 to 4 cm (1¼ to 1½ in) tall and 2 cm (¾ in) broad; the flower shape has been compared to a policeman's helmet, giving rise to the alternative common name Policeman's Helmet. Although it does not range all over India and is by no means the only Impatiens native to that country, it is also known as Indian Balsam in countries where it is introduced.
After flowering between June and October, the plant forms seed pods 2 to 3 cm (¾ to 1¼ in) long and 8 mm broad (¼ in), which explode when disturbed, scattering the seeds up to 7 metres (23 ft). Impatiens, meaning "impatient", refers to this method of dispersal. The green seed pods, seeds, young leaves and shoots are all edible.
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 the United States), 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. In the UK the plant was first introduced in 1839 at the same time as Giant Hogweed and Japanese Knotweed.[1][2] 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 geenhouses of the rich. Within ten years, however, Himalayan balsam had esaped from the confines of cultivation and began to spread along the river systems of England.[1] Today it has spread across most of the UK and some local wildlife trusts organise "balsam bashing" events to help control the plant.[1] 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. Regarding stands of the plant at forest edges and meadow habitats, they caution that these conclusions do probably not hold true; in such localities, manual destruction is apparently still the best way to stem or slow the expansion of Himalayan Balsam.
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.