The wondrous Fallopia Japonica here muscling out of its host sites in and on the peripheries of Standish Hospital, Gloucestershire. Browse the following pics for more detail and some knotweed reflections.
If you live in the UK and step out of your house, you are at most, 6 km from an infestation of this plant..unless you live in the Orkneys. Fact and myth surround the Japanese knotweed, of which there are 6 variants...but all plants are clones of the original females introduced 200 years ago.
Its impressive pugnacity can be understood by its original Japanese rocky volcanic habitat, as it is highly resistant to burning, divides and grows swiftly when soil is disturbed and quickly estabish roots several metres in all directions.
Spreading or breaking plant material will categorically ensure its establishment elsewhere: 0.7g of root material(little fingernail sized) will result in a new plant, which will grow easily over 2 metres in a season. Without fail, wherever there is a mature specimen, its undergound rhizomes will already have established up to 7m horizontally and 3-4m vertically.
It is currently offence to "plant or cause to grow" this in the UK(though not to already have it!)...as it is to allow it to spread beyond one's land/property. The legal onus is immediately on its owners to eradicate the plant: one would imagine that sheer neighbourliness and even moral sensibility are enough to motivate...mind you, ignorance and being incorrectly or under-informed are forgivable states of mind. Er, but once you're informed.....
Currently site developments in the UK can expect a 10% addition to their costs, if the site contains Japanese knotweed, because of the nature of eradication,removal and containment.
The plant self-replicates mechanically, not sexually(a clone, see above): so, soil disturbance, machinery, footwear, garden implements, water, tipping all cause vigorous new colonies. It thrives if attempts are made to compost it; it will certainly grow from deep below refuse tips and through concrete.
2012 Olympics organisers have spent 4 years on its eradication since it managed to invade its sites.
It can indeed be eradicated: remedial action planners need to be aware of costs and time: the quickest and most effective methods are by far the dearest, with any planning to cover a span of several years. It is the only plant ever to generate the implementation of a biological control, though this is presently at the testing stage.

All images in these 2 galleries were taken with a Canon 1Ds series full-frame camera with a Canon 70-200mm f4L(IS) zoom telephoto. All images are tagged and copyrighted, and are the property of myself.

SR May 2012

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