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.
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.
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.
NAPHTHOQUINONES in BALSAMINACEAE FAMILY
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,
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.