Why do weeds exist

Not for ethical reasons, but for typological ones. A weed is such a non-specific term. So homogenising and unsophisticated. So structuralist. Each so-called weed, after all, has a remarkable story to tell. Each is the product of millions of years of evolution. Each is a descendant from an ancient species that had migrated across seas and continents.

Each has a life trajectory — dormancy, germination, establishment, secondary growth, bolting, pollination, seed dispersal, reproduction, death, decomposition. Each has shoots, buds, stems, leaves, leaf stems, roots, fruit, bulb, stolon, flowers, dermal tissue, ground tissue, vascular tissue, nodes.

Each employs sunlight, devours nutrients, absorbs water, consumes carbon dioxide, produces sugars, exudes oxygen. Each is a habitat for a bee, a slug, a gnat, a caterpillar, a snake, a frog, a skink, a greenfly, a spider, a mite. Where do these creatures go when their source of nutrition and shelter is branded distasteful and cast aside?

When it comes to weeds, context makes all the difference. Here, for example, is a little patch meant for a pepper plant. As I water it, eminium seeds begin to sprout. After lingering in the dirt for what may have been many summers, they finally get their turn in the sunlight. They earn my admiration when they grow into a patch of green in an otherwise grey sandy landscape.

Something from the botanical gardens, perhaps. And they make a lovely decoration for my pepper. But when, ungratefully, they grow further still, they turn bothersome. They pose a threat to my pepper plant, taking away sunlight, water and fertiliser that was meant for it — not them. And so, in four or five tugs, I uproot them completely. Or this seemingly harmless shrub, the Syrian mesquite , with its small bright-green leaves. This unimpressive-looking bush has sharp little thorns that pierce right through the gardening glove.

Weeds are common on all million acres of U. Since weeds are so common, people generally do not understand their economic impact on crop losses and control costs. Another source estimates that U. Also, weed control and other input costs e. Several factors help determine the relative costs of herbicides from one crop to another and include the competitive ability of the crop, the weeds present, the contribution of non-chemical control practices, the tillage method, management decisions, and the value of the crop.

Ross and Lembi, Despite the negative impacts of weeds, some plants usually thought of as weeds may actually provide some benefits.

Some attributes include:. Let's Stay Connected. By entering your email, you consent to receive communications from Penn State Extension. View our privacy policy. Thank you for your submission! No matter what definition is used, weeds are plants whose undesirable qualities outweigh their good points. Ligenfelter, Extension Agronomist, Department of Agronomy, Penn State University Description of a Weed There are numerous definitions of a weed, including: a plant out of place and not intentionally sown a plant growing where it is not wanted a plant whose virtues have not yet been discovered.

Emerson plants that are competitive, persistent, pernicious, and interfere negatively with human activity Ross, et. Get the latest updates in news, food, music and culture, and receive special offers direct to your inbox. Support Us South Florida's independent source of local news and culture. I support. Support the independent voice of South Florida and help keep the future of New Times free. Support Us.

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