The first weeds were created 10,000 years ago, when the first fields were cultivated, and the concept of the botanical trespasser—the "plant in the wrong place"—was invented. Seven thousand years later, Middle Eastern farmers, still disgruntled at having lost their hunter-gatherer lifestyle, wrote a creation myth in which agriculture and its accompanying weeds are a celestial punishment for their cleverness. Genesis' god condemns errant humans to till the soil "in the sweat of they face ... cursed is the ground for thy sake ... thorns and thistles shall it bring forth to thee."
Today the thorns and thistles are still there and more is spent trying to exterminate weeds in farms and gardens than on any other aspect of cultivation. Their appearance sparks reflexes, not reasoning. They are regarded as inexplicable and impertinent intruders, quite unconnected with the way we live our lives. But the fact is that we are responsible for weeds. Every single nuisance, from the purslane and witchweed in the cornfields to the thown-out aquarium exotics now smothering the native flora of the Everglades, is a consequence of our thoughtless and sometimes deliberate disruption of natural systems, ploughing, spraying, moving species way beyond their natural homes.
We tend to ignore that weeds are beneficial. They are nature's pioneers, abhorring the vacuum of barren earth, sometimes functioning as a kind of ecological immune system: organisms which move in to repair damaged tissue, in this case earth stripped of its natural vegetation. Certain weeds are more directly useful for humans. The wheat on which western civilization is predicated began as a weed grass: wild emmer.St John's wort (klamathweed) is now a recognized and widely used anti-depressant.
We couldn't survive as modern humans if we ceased to control weeds. It's impractical to let them grow unimpeded. But, every once in a while, perhaps we should take a break from weed-whacking and examine our relationship with these clever and resilient plants, if only to admire their will to live and to multiply.
View a slide show by Richard Mabey on weeds that expands on this introduction.