Bohemian knotweed is a rare hybrid of the notorious Japanese and Giant knotweeds. Unlike its ‘parent plants’, however, it is not so easily recognised, which makes it particularly troublesome.
Experts at Environet UK, an invasive plants specialist, are now bringing it to the public’s attention in a bid to raise awareness after the weed was discovered by a homeowner preparing their house for sale.
The discovery was made in Aylesbury, Buckinghamshire by Stuart Marshall (pictured) who inherited the property and was renovating it to sell.
He said: “I was clearing the garden when I came across the plant which seemed to be growing vigorously, but otherwise didn’t look particularly menacing. I only became suspicious that it might be invasive when my attempts to remove it failed.
Marshall put in a call to Environet, which soon identified it as the unusual variety of knotweed which can be just as invasive and vigorous as both its parents.
Bohemian knotweed is in fact produced by a cross fertilisation between Japanese knotweed and Giant knotweed.
However, unlike it’s parent plants, it has the potential to produce male plants and set seed, enabling it to spread more rapidly. What’s more, the fact that it’s not so easily recognised means it is often left to grow unchallenged.
Its vast root system, Environet explained, meant it had the potential to cause damage to property, including patios and driveways – this is something which is seldom covered by buildings insurance.
For this reason the advice is the plant should be treated or removed as quickly as possible.
Nic Seal, Founder and managing director of Environet UK, said: “Stuart’s decision to act quickly and decisively means the infestation can be removed and his sale should proceed unhindered.
“While Japanese knotweed is by far the most prevalent variety, all types of knotweed are potentially problematic and should be dealt with quickly to avoid risk of damage to property, legal cases relating to encroachment or problems selling in the future.
“Evidence of a professional treatment plan and an insurance-backed guarantee for the work should be enough to satisfy any mortgage lender, although sellers may find there’s still some diminution in the value of the property due to the associated knotweed stigma.”
From the legal perspective, homeowners are advised – when asked the direct question regarding invasive plants – to declare the presence of Bohemian knotweed if they’re aware it is, or has been, growing on their property to avoid the risk of future legal action against them, even though strictly speaking it is not Japanese knotweed.
How to identify Bohemian Knotweed
- It has green leaves which are either heart shaped or square ended. Both types can appear on the same plant.
- Leaves are larger than Japanese knotweed, but smaller than Giant knotweed, and have short hairs on the underside.
- Plants usually grow two to three metres high.
- It blooms in late summer, with small green-white or cream-white flowers that grow in plumed clusters.
- Cane-like stems are reddish-brown in colour. The plant dies back above ground in the autumn, but the canes usually remain standing.
