The philosophy and ethics of weed

To a gardener weeds are plant growing at the wrong place and/or the wrong time (nettles where once a sought after delicacy). To the cryptoforester weeds (as you call them) are a source of inspiration.


Peter Del Tredici is a Harvard biologist with a special interest in weeds and 'emergent forests', these are quotes from the Boston.com website.

The very characteristics that most people deride are ones that Del Tredici admires. He calls this area an “emergent forest,” an ecosystem formed spontaneously without the help of human hands. Those thin trees, for instance, are ailanthus trees, featured in the book “A Tree Grows in Brooklyn” — planted originally for ornamental purposes, but now flourishing on their own because of their ability to grow by cloning themselves at the roots. “I don’t think anybody has planted an ailanthus tree in 100 years, yet it is the most common tree in most northeastern cities by a long shot,” Del Tredici says. The phragmitis reeds, which also fill the Back Bay Fens, are able to thrive in highly degraded wetlands like this one, where they help clean polluted water.

What some people see as a collection of undesirable plants, Del Tredici views as a valuable ecosystem that’s unique to the hostile habitat of the city.

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“I consider ‘weed’ to be a politically incorrect term,” he says. “There is no biological definition of the term weed. It’s really a value judgment.”

If we saw this motley collection of plants differently, Del Tredici suggests, we’d realize they’re a kind of marvel: living things in the harsh and stressful urban landscape that don’t just survive there, but thrive. With no effort on our part, they fill the city with greenery, providing cleaner air and water, shade, and food and habitat for wildlife. They do it without expensive fertilizers and irrigation. It’s time, he suggests, that we learned to embrace them — to stop thinking of them only as weeds to uproot, and start considering what they have to offer.

English nature writer, forager, and crypto-forester avant-la-lettre Richard Mabey has devoted an entire book to weeds. The Guardian writes:

Professor Edward Salisbury, director of Kew from 1943-1956, once cultivated 300 plant species from the dirt he found in his trouser turn-ups. 

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We may hate them, but there is no question that they succeed as they do partly through our efforts. Large areas of Florida are now under threat from paperbark trees introduced to the Everglades in order to drain the land and thus make it suitable for development. And as Mabey notes, the UK's three Most Wanted superweeds were all deliberately introduced to this country.

Giant hogweed, Indian balsam and Japanese knotweed were each brought to Britain in the mid-19th century as garden ornamentals. It didn't take long before giant hogweed went native, absconded from its original home in Buckingham Palace Gardens and colonised London's canal system. Knotweed went one step further, demonstrating a Hulk-like ability to rip through pavement slabs and muscle through brickwork. It's now considered such a threat that eradication programmes cost the taxpayer £150m a year.

Richard Mabey writes about weeds with the confident affection of someone discussing old friends – which many of these plants must now be. Back in 1972, he went for a walk from his office in London and happened upon what he called the "unofficial countryside": abandoned or forgotten scraps of the city in which plants and wildlife thrived. At the time his interest in those urban scraps was taken as no more than a hippy-ish novelty, but in the years since he took that first walk, the rest of the world has caught up with him. Urban planners have recently made the astounding discovery that plants and wildlife can get on with being beautiful and regenerative without any outside assistance. When weeds colonised an abandoned section of New York's high-rise railroad, the inhabitants of the Upper West Side were split between those who wanted the High Line demolished and those who liked looking out on a vagrant landscape of irises, daffodils and rogue Christmas trees. The preservationists won and the High Line reopened in 2009 as Manhattan's newest slice of urban parkland.