In 1847, a vigorous bamboo-like plant with bracts of pretty white flowers won the gold medal for best ornamental plant at the Society of Agriculture and Horticulture in Utrecht.

 

This sample of Japanese knotweed (Raynoutria japonica) had been brought from Asia by the Bavarian plant collector Philipp von Siebold and, by 1850, he had sent a cutting to Kew Gardens.

 

From this, further cuttings were taken and shared by gardeners all over the country.

 

William Robinson, the Irish horticulturist and author of the influential 1870 classic The Wild Garden, loved it: “In the pleasure ground or plantation, or by the waterside where there is enough soil, they may be very handsome indeed”.

 

A century and a half later, Japanese knotweed is a notifiable weed costing the UK an estimated £1.25 billion a year to control.

 

Failure to report it or prevent its spread can earn you an ASBO; its presence on or even near your property is enough for you to be refused a mortgage.

 

The average UK city contains 60,000 tons of knotweed – it is very difficult to eradicate once it has taken hold.

 

In 2013, a lab technician in Rowley Regis was driven to murder his wife and then commit suicide as he was so tormented by a patch of knotweed that had appeared in his back garden.

 

This salutary tale of unintended consequences sums up our ambiguous relationship with weeds.

 

In his history of that relationship, Weeds, Richard Mabey describes them as “not only plants in the wrong place, but plants which have slipped into the wrong culture”.

 

The history of our species, as we developed from hunter gatherers to farmers, can be framed as a battle with the ‘wrong plants’, the ones that attack or undermine food crops, or choke out our preferred ornamentals.

 

Anyone with a garden knows the old enemies: bindweed, nettles, ground elder, cleavers. And we can only admire their vigour, their resourcefulness.

 

The American garden maven Dianne Benson catches this perfectly in her book Dirt: “They know, they just know where to grow, how to dupe you, and how to camouflage themselves among the perfectly respectable plants, they just know, and therefore, I’ve concluded weeds must have brains.”

 

Rather than to impute demonic intelligence, a more productive way to approach weeds may be to see them as indicator species, canaries in the mine of our troubled relationship with nature.

 

After all, it is our decision to cultivate some plants but not others that creates the space into which weeds have so happily spread. As Richard Mabey puts it: “Weeds are our most successful cultivated crop.”

 

Thinking differently about ‘weeds’ forces us to think differently about what is or isn’t ‘natural’. The foraging movement has reminded us that almost all the weeds we fight against can be eaten and many contain chemical compounds that could help us live healthier lives.

 

We may never beat Japanese knotweed. But, in the meantime, we can pickle its young shoots, serve it as vegetable and use it to flavour our vodka.

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