Impatiens glandulifera

Balsam Family [Balsaminaceae]  

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August, Fletchers Branch, Manchester Bolton & Bury Canal. Photo: © RWD
Flowers can be white, pale pink, darker pink or red.

August, Turton & Entwistle Reservoirs, Belmont, Lancs. Photo: © RWD

August, Fletchers Branch, Manchester Bolton & Bury Canal. Photo: © RWD
The fruit pods are also 6-sided as are the main stems. Flowers are zygomorphic (with bilateral symmetry) with a large upper petal and slightly narrower but longer lower petal which is cut down the middle into 2 parts. there is a large opening in the centre where the sex organs lurk.

August, Fletchers Branch, Manchester Bolton & Bury Canal. Photo: © RWD

August, Fletchers Branch, Manchester Bolton & Bury Canal. Photo: © RWD

August, Hollingworth Branch of Ashton Canal, Daisy Nook. Photo: © RWD
The leaves of a young plant only a foot tall as yet.

5th Sept 2011, Tame Valley, Greenfield, Gtr M/cr. Photo: © RWD
Seed pod on right is ready to contract into a spiral, squeezing the seeds out like a hand squeezing a wet bar of soap. The seeds are either flung out or squeezed out at such speed as to throw them up to 5 metres. Seed pod on left has already triggered but not all the seeds have been squeezed out, several remain half inside and one is half exposed.

5th Sept 2011, Tame Valley, Greenfield, Gtr M/cr. Photo: © RWD
When ready, the slightest touch on the pod will result in the pod splitting explosively. Here the process was hindered by human hand, resulting in some of the seeds remaining within the spiral.

5th Sept 2011, Tame Valley, Greenfield, Gtr M/cr. Photo: © RWD
Ripe seeds are brownish, un-ripe whitish. Between 5 and 10 seeds are held poised within a seed pod.

10th May 2015, woods, Nob End, Bolton, Lancs. Photo: © RWD
Carpeting the woods as far as the eye can see and further too, 360° around your Author in fact. These are the young cotyledons of Himalayan Balsam just emerging above the soil after winter, ready to overwhelm the woods.

17th April 2015, Aldford, River Dee, Cheshire. Photo: © RWD
They smother the ground of woods in early spring with cotyledon 'leaves' (the opposite pair of nearly-round, pale-green, un-toothed projections with a nick at the end).

14th April 2015, Yarrow Valley Country Park, Chorley, Lancs. Photo: © RWD
The cotyledon 'leaf' pairs are not really leaves, but the first thing to sprout up from the ground in dicotyledon plants.

17th April 2015, Aldford, River Dee, Cheshire. Photo: © RWD
The un-toothed dicot (dicotyledon) 'leaf' pair, plus two pairs of real toothed leaves springing up, which already have reddish mid-ribs.

25th Sept 2015, Mytholmroyd, West Yorkshire. Photo: © RWD
When Himalayan Balsam is up-rooted or badly hacked about many reddish-purple adventitious roots sprout out from every node, of which there are many. Adventitious roots will take root again in the soil, but Himalayan Balsam, being an annual, will die over winter so it should be alright unless it has time to flower and set seed again, in which case it will propagate.

11th June 2016, Cronton ex-Colliery reserve, Merseyside. Photo: © RWD
Your Author is fascinated by the plastic geometry of this now almost ubiquitous and certainly notorious plant. Almost without exception, a young plant which has progressed beyond the cotyledon stage has two tri-stars of three leaves at the top followed by a 4-star quadruplet. The topmost two 3-whorls of leaves are set at 60° to each other whilst the lower 4-whorl must(?) be set at an arbitrary angle to the upper two whorls (3 into 4 is not an integer). So, the same plant has leaves in whorls of 2 (dicotyledon and two early whorls) 3 and 4. How strange. Moreover, the main stems are hexagonal.

Your Author looked at older plants, and sure enough, it is only the bottom-most whorl that has 4 leaves, all the higher whorls are in 3's, set at 60° to each other. Both initial pairs of 'leaves/cotyledons' when the plant first emerges are no longer extant; they must have been discarded.

An annual which usually grows up to 2m in height, but can reach 12 feet! Likewise the stems can be up to 10cm thick, usually maybe about 3cm. It is native to the foothills of the Himalayas, India and Pakistan.

Himalayan Balsam is another weed which is out of control in the UK. It colonizes the banks of fresh-watercourses very easily, both rivers and canals. The weed can be removed manually by pulling, when the roots and all are extricated. But any piece of stem which includes a node left on the ground can take root again by means of adventitious roots which emerge from the nodes, so all bits should be removed. Any seeds are viable for only two years. Just one plant can produce 800 or more seeds. However, it does not set seed unless aided by visiting insects because of a special pollination mechanism: the stamens form a conical shape which completely obscures the stigma beneath. Pollen release only occurs over about 2 days when visiting insects, usually bees, get pollen covering their backs and then depart. When the cone of stamens shrivel away this uncovers the stigma beneath allowing pollen-bearing bees to enter depositing the pollen on their back to the stigma. The nectar accumulates in a broad spur at the rear of the flower. During the period the flowers produce a strong sickly scent. The plant can also re-grow vegetatively from any stem node - where adventitious roots develop if the plant is uprooted. But because Himalayan Balsam dies off over winter and regrows from seed the next year which was flung out up to 7m by nearby plants.

It is not, as some sources suggest, sterile but does produce viable seed after all!

Biological control of this weed also seems possible. Researchers have found a Rust Fungus in the Indian Himalayas which attacks and degrades Himalayan Balsam and which seems to be highly specific to that plant; a rust fungus that also turned out to be completely new to science, so a scientific binomial name is being sought. The rust is awaiting approval from the UK regulators before it can be used in the open in the UK. The rust fungus belongs to the Puccinia Genus and is a five spore staged rust fungus which infects the stem and leaves of the plant throughout the season, and which crucially completes its entire life cycle on this one single species. It has since been discovered that this rust is new to science, so has been named Puccinia komarovii var. glandulifera var. nov in a reference to its affinity for preferentially attacking Himalayan Balsam. It has only been tested on 84 plants in 74 species plus an additional 10 species of ornamental species widely grown in the UK without attacking any other, so is presumed safe. It gained approval for release by Defra in 2014 and trials were conducted and in the wild at three specific locations in July 2014, which it passed with flying colours. In Spring 2015 it was released nationwide and a monitoring program instituted. So far, September 2017, your Author has noticed no difference whatsoever in Himalayan Balsams occurrence nor spread! The authorities seem to be waiting for the rust to spread naturally, which it is, but very slowly. The trouble seems to be that the rust does not always over-winter at some sites. It could be decades before any difference is noticeable nationwide. Also, unfortunately, the rust can infect other non-invasive species of impatiens (Balsams), but so far not Orange Balsam.

The flowers smell sickly sweet, and, according to some, the crushed stems and leaves smell like Jeyes Fluid. The seed pods, when ripe and touched, suddenly release pent-up elastic energy, catapulting the seeds out up to a distance of 12 metres. It thus readily spreads, especially beside streams where the seeds can be transported by the flowing water.

There are some saving graces to this plant: it looks nice when in flower (which is why it was imported into this country many decades ago), and the flowers attract many bees, which in recent years have been seen a drastic and worrying decline since they are the main pollinators of some flowers (and crops).

It is recounted that children used to carefully collect a handful of ripe seed pods and then squeeze them. This triggered their explosive curling and felt like a lot of wriggling squirming worms within the closed hand. The seeds, which number 5 to 10 within one pod, can be flung out at such high speed that they are thrown up to 5 metres. If they land in flowing water, they will be carried to pastures new, but always near water, for the plant likes dampish ground.



Balsaminol and its near-dimer Impatienol are NaphthoQuinones found in Himalayan Balsam and other members of the Balsam Family (there are two carbon atoms less in Impatienol than in two molecules of Balsaminol.

The two are also found as the sodium salts, Imptienolate and Balsaminolate.

 Lawsone, also known as Hennotannic Acid, is found not only in members of the Balsam Family but also in the Henna plant (Lawsonia inermis), extracts of which have been used for dying hair for the last 5000 years. Lawsone reacts chemically and permanently with the organic plastic keratin found in both skin and hair turning it a shade of brown similar to a sun-tan. The coloration lasts until the hair or skin is shed.

Lawsone also absorbs strongly in the UV part of the spectrum and is used in sunscreens which also tan at the same time without the aid of the sun.

Lawsone is isomeric with Juglone, but has the hydroxyl group attached to the other ring instead. Juglone is found in Walnuts and stunts the growth of many plants, inhibiting certain enzymes in the metabolic processes, but Maple, Birch and Beech are immune to its effects. When botanists realised that Juglone has herbicidal properties they began utilising it as a herbicide, but it is also highly toxic to insects which feed on herbs too and other herbicides were developed based upon it. Juglone itself is brown and toxic to certain insects and has been used in hair dyes, inks, a food colouring agent and as a herbicide. Together, Lawsone and Juglone are the only two known mono-hydroxy 1,4-naphthoquinones found in nature (although many derivatives are known).

Many 1,4-Naphthoquinone derivatives are part of the Vitamin K group of compounds, such as Phylloquinone and Vitamin K1 which are synthesized within many plants.


Analysed by the latest most accurate chemical analysis methods (GC-MS) it has been reported that α-Pinene, β-Pinene, Camphene, 1,4-Cineole, 1,8--Cineole, d-Limonene, α-Terpinolene, 1-Terpineol, α-Terpineol and β-Terpineol are volatile components of the sweet smell.

In addition to the above, Himalayan Balsam was found to contain β-Phellandrene (which is absent from Touch-me-not Balsam below.

In addition to the above compounds, a further 3 organic volatiles were found in Touch-me-not Balsam (Impatiens noli-tangere): (Z)-Ocimene, Fenchol and Geraniol.

  Impatiens glandulifera  ⇐ Global Aspect ⇒ Balsaminaceae  

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Impatiens glandulifera

Balsam Family [Balsaminaceae]  

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