In defense of botanical trespassers.
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."
Below we view a slide show by Richard Mabey on weeds that expands on this introduction.
A cosmopolitan family of semiparasites that come in all manner of varieties, each chemically adapted to a specific host. Dodders have no chlorophyll and no roots. The growing stems edge forward with the coiling movements of sidewinders, until they chemically “sniff” their host, and then head toward it, suckering spikes at the ready. The variety that preys on tomatoes has been filmed rejecting globes of red liquid and dyed tennis balls, and slithering decisively toward a piece rubber impregnated with tomato-scent chemicals.
Most American weeds originated in Europe, a legacy of colonialism that outstayed the colonists. Burdock’s floppy gray-green leaves were a favorite foreground ornament of 17th- and 18th-century landscape painters. But it’s had a more modern practical use. The seed-heads—called “burrs”—are covered with hooked spines, which attach themselves to passing animals and get dispersed. In the 1940s the Swiss inventor George de Mestral, removing a bushel from his dog’s fur, was inspired to create Velcro. It was patented in 1951, one of the first examples of the burgeoning science of bio-engineering.
One of the most enchanting European wetland flowers. The pre-Raphaelite John Everett Millais painted its magenta sprays on the riverbank in his famous picture of the drowning Ophelia. It arrived in the New World in the early 1800s, probably as a stowaway in ships’ ballast. It came without any of the munching insects that, above and below ground, keep it in check in Europe, and took off west like any other ambitious immigrant. It has now reached the fragile marshlands of Alaska, forming solid stands—a mile thick in places—which even muskrats cannot penetrate.
Sounds as American as hillbilly, but is another settler introduction. Meadow-grass is a widespread European weed-grass and was introduced to the United States in the fodder, or attached to the hooves, of their cattle. Adapted to the heavy grazing—and heavy hooves—of domestic stock, it soon ramped across grasslands east of the Mississippi, and drove most of the more delicate indigenous grasses close to extinction. But it was good feed and a boon to ranchers, who rebranded it, immortally, as “Kentucky blue grass.”
Not all weeds are, so to speak, “weedy.” Many tree species can behave with the enterprise of wheatfield invaders and flower-border guerrillas. Tree-of-heaven is a popular Chinese ornamental with prodigious powers of both seeding and vertical growth. It gets its name not from some paradisiacal scent (the flowers smell rather disagreeable, but are popular with city bees), but from the speed with which it rockets skyward, sometimes carrying sidewalk slabs with it. In the U.K., during a rubbish collectors’ strike, trees-of-heaven were seen shooting out of unemptied refuse bins. They are one of the great healers of broken and derelict city space, as in Detroit, and already a key component of the post-industrial urban forest across the northern hemisphere.