Photo by Getty Images/Goja1
A weed’s ability to quickly colonize bare ground didn’t develop by accident. Most weeds evolved their “live fast, reproduce a lot” behavior over many hundreds of thousands of years. Before humans began working the earth, avalanches, fires, and animal activity disturbed the soil, opening up gaps that gave space for opportunistic weeds to germinate. At the same time, animals roaming the Earth ate seeds, which, once excreted in feces, rapidly germinated. The planet’s dense coverage of woodland, scrub, and grasslands, meanwhile, kept these plants in check.
About 12,000 years ago (during the Neolithic era), greedy plants won the lottery when humans first began to work the land. Weeds had a field day — literally. In the first steps toward formal agriculture, humans cleared vast areas to grow crops, inevitably becoming the first sentient beings to contend with weeds. Over the millennia that followed, as we felled more forests and created more fields, the weedy situation escalated.
Evidence suggests that many weed species have adapted to coexist with human activity, making it easier for them to exploit the land around us. Some weeds have increased both the speed at which they reproduce and the quantity of seed they produce. A matter of natural selection, those plants that happen to produce more seed faster than their relatives will eventually outcompete and become the dominant strain.
If there’s one weed in your garden that’s particularly annoying, it’s probably been living with humans for a long time, which has helped it to evolve into its current, bothersome strain. Every time we remove or dig out weeds, the strongest survive and regrow, contributing further to the “weedvolution.” It’s not the weed’s fault it’s so weedy — it’s ours.
The First Weeds
Fossils tell us that weeds existed millions of years ago, but since these fossils are the only early records we have, we may never know exactly when weeds first evolved. We do know, however, that some of the first successful plant groups were the spore-producing field horsetails and ferns, their descendants being today’s common garden weeds.
In 2015, ecology professor Sergei Volis published a research article that gave evidence of 13 well-known weeds — including dense-flowered fumitory (Fumaria densiflora) and milk thistle (Silybum marianum) — used as human food in a 23,000-year-old camp on the shores of the Sea of Galilee in Israel. The camp comes from our hunter-gatherer era, long before the time when humans cultivated plants as food. Volis believes that this earliest example of a human-disturbed environment paved the path for “proto-weeds” (the first wild plants to thrive in human-affected habitats).
Evidence of the human veneration of weeds comes from paintings and murals dating as far back ancient Egypt, with images of a species of Convolvulus (a bindweed) used as a symbol of respect or mourning.
Through the ages, alongside paintings of cultivated flowers, such as tulips and roses, weeds (dandelions and daisies among them) appear regularly, even in medieval sculptures and carvings. Victorians, known for their particular love and fascination of the natural world, were perhaps ahead of their time. Weeds regularly appeared in the most popular Victorian fashions and in designer patterns for wallpapers and upholstery fabric. (To see for yourself, visit your nearest art gallery or museum and see how many weeds you can spot in the artworks.)
Contemporary art hasn’t forgotten the humble weed: Graffiti and household furnishings still use weeds as symbols of nostalgia or wilderness, and even possibly as a nod to rebelliousness.
Weeds for Well-Being
Although the earliest gardens on record were primarily for produce, they also served as places of rest and reflection. For example, 15th century monks at Mount Grace’s Carthusian Priory in North Yorkshire used their private garden “cells” as a means to aid mental well-being. For medieval Christians, in particular, a garden provided a link to God and the Garden of Eden; paradise gardens acted similarly for Muslims. These gardens often included flowering weeds as ornamental additions to bring a sense of peace to the area, and the gardener.
Photo by Getty Images/Pilat666
Many medieval gardens provided plants for medicinal use. Among them were weeds we know today: dandelions (Taraxacum officinale), red valerian (Centranthus ruber), yarrow (Achillea millefolium), and many others. These past gardeners believed that yarrow plants helped ease the pain of headaches and serious wounds. If our ancestors could grow, manage, and use these plants as food, medicine, and ornamental additions to their gardens, why can’t we?
From the Farmland
Rebel plants are the biggest adversary to farming. Weeds, such as cornflower (Centaurea cyanus) and common poppies (Papaver rhoeas), grow on bare, disturbed ground — so when farmers turn their fields, they provide the largest expanses of land on which weeds can thrive. Problems arise when weeds compete with crops for sun, water, and nutrients, affecting the harvest.
For farmers, the worst event of all is when a weed mixes with a crop, rendering the crop unusable. Some wild grasses have evolved through human attempts to eradicate them, gradually mimicking crops, such as wheat and rice. We try to weed them out, but we inevitably miss the weeds that look most like the crop we’re growing. Over centuries, those clever weeds have outsmarted us, becoming more and more similar in appearance to the plants we’re trying to cultivate, increasing the their chances of survival and their ability to proliferate.
Photo by Getty Images/Martin Wahlborg
It’s not just crop farmers who suffer from the nuisance of weeds. Some weeds are poisonous to livestock. Typically, animals are smart enough to avoid plants that harm them. However, where livelihood and life are concerned, farmers are right to protect their livestock by removing as many of those dangerous weeds as they can with modern techniques and solutions.
And, indeed, farmers have been fairly successful over the last century at this task — using weed killers to help them. There’s no question that, where farming is concerned, weeds need a heavy hand. The unfortunate side effect, though, is that the diversity of all wild plants on farmland has fallen significantly as a result.
Some of the world’s best-known weeds traveled far from their natural habitats, brought on ships from across the seas. Over centuries of exploration and colonization, seafarers have, knowingly or unknowingly, carried weeds on their ships and introduced them to shores far from home. In the 15th century, weeds traveled from Europe to the Americas, and in the 18th century, they moved from Europe to Australasia. Away from their natural habitats and the evolved pests and diseases meant to keep them in check, rebel plants found new and abundant life, reproducing in vast quantities and dominating the landscape. These rebels turned into tyrants, rampaging through lands and taking over weaker species, not in a trickle, but in an unstoppable flood.
This weedy spread has continued right up until the present day; it’s only the turn of the new millennium that’s seen humankind take significant steps to stem the flow of invasive species. Thousands of weeds, though, are now so widespread that it’s impossible to remove them completely, and some, such as species from the Brassica genus, create real problems for native plants in the United States.
When Ornamental Plants Rebel
Plant hunting reached obsessive levels during the Victorian era, when wealthy landowners funded expeditions to discover and introduce new plants to ornamental gardens back home. However, these introductions happened without anyone fully realizing the growth habits of these new plants.
In 1850, Kew Gardens in the United Kingdom imported Japanese knotweed (Reynoutria japonica), describing it as one of the stateliest ornamental plants of the time. It was quickly distributed around the country via vegetative propagation. Thankfully, the introduction was male, which limited the rate of its spread; the plant, being dioecious, needed a female partner to produce seed.
Fox and cubs or fox-and-cubs, Pilosella aurantiaca. Photo by Getty Images/hekakoskinen
Yellow skunk cabbage (Lysichiton americanus), on the other hand, had a more successful spread. Introduced to the U.K. as an ornamental in 1901, it became an illegal invasive alien species in Europe in 2016. So while you can still grow it under controlled conditions if it’s already in your garden, it’s now illegal to introduce in Europe.
Many plants we now consider weeds for their rebellious behavior began life in our soils in this way. Purple toadflax (Linaria purpurea), evening primrose (Oenothera biennis), fox-and-cubs (Pilosella aurantiaca), baby’s tears (Soleirolia soleirolii) — our recent ancestors brought all of these and more to our gardens, planting them because they thought they were beautiful.
When Rebels Become Good
While some rebels continue to rage as weeds, other plants have crossed over to the good side. Though we should still consider them weeds, they’ve somehow made it into our hearts and minds as precious garden plants. By labeling them as “wildflower” and “self-sower,” we’ve glossed over the fact that these plants behave like any other weed. Here are some rebels that’ve turned good.
Snapdragons. Photo by Getty Images/baona
Snapdragon (Antirrhinum majus)
Commonly sold as a garden plant, snapdragon is as tough as any other weed, happily seeding into cracks in medians, walls, and any other dry, sunny spot.
Foxglove (Digitalis purpurea)
Foxglove self-seeds heavily in sunny conditions. Without restraint, these plants will create vast stands of flowers. They’re poisonous to humans if eaten.
Latin American Fleabane (Erigeron karvinskianus)
This garden plant exhibits worse rebel behavior than most weeds! Beautiful white flowers fade to pink throughout summer and fall, self-seeding everywhere. U.S. native seaside daisy (Erigeron glaucus) behaves similarly.
Bluebells. Photo by Getty Images/Peter Llewellyn
English Bluebell (Hyacinthoides non-scripta)
Native to Western Europe, English bluebells create beautiful, blue, woodland carpets across the U.K. Away from the tough growing conditions of the dry shade of trees, however, this plant can turn problematic. Not to be confused with the native Virginia bluebells (Mertensia virginica), an entirely unrelated plant.
Forget-Me-Nots. Photo by Getty Images/lior2
Forget-Me-Not (Myosotis sylvatica)
Forget-me-not seeds itself thickly, yet we let it off the weedy hook thanks to its beautiful blue flowers.
Primrose. Photo by Getty Imaages/Kerrick
Primrose (Primula vulgaris)
A clear sign of spring in the U.K. and some areas of the U.S., primrose often pops up weed-like in lawns and damp, shady spots.
Great Mullein (Verbascum thapsus)
With soft, silvery leaves and tall spikes of yellow flowers during summer, great mullein makes itself at home in dry, sunny soils.
More Than a Pretty Petal
We’ve accepted the majority of weeds into our precious gardens solely based on their looks, but some we’ve developed a deeper connection with throughout history. For example, in the U.K., the common poppy became the most recognizable and enduring symbol of those who lost their lives in World Wars I and II because of its presence on the fields where troops had been killed.
Fireweed. Photo by Getty Images/Melissa Kopka
The Blitz from 1940 to 1941 saw German bombs level large areas of London. Among the rubble and devastation, though, came weeds — the first signs of new life from horror, symbols for a country that needed to begin its process of healing. Reports from the time suggest a widespread proliferation of fireweed (Chamerion angustifolium), which seized its opportunity to colonize craters in places it’d rarely been seen before.
An Urban Future
The factor that links all weeds — whether native or introduced; gentle rebel or marauding tyrant; medicinal or harmful — is humans. Weeds are a very human problem. A weed without humans is just a plant, whereas a plant that causes problems for humans is a weed. This has always been so.
Experts estimate that about 68 percent of humans will live in cities — an unnatural habitat that we’ve created — by 2050. However, this urban setting doesn’t seem to be a deterrent for weeds. In fact, weeds appear to be the first plants moving into cities with us, easily adapting to this new environment. If our relationship with weeds has always been a close one, it seems it’s about to get even closer.
Cover courtesy of Laurence King Publishing Ltd
Excerpted from Wild About Weeds by Jack Wallington Copyright © 2019 by Jack Wallington. Excerpted by permission of Laurence King Publishing Ltd. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.