Why Are Weeds Persistent?

Weeds in Waterloo, Ontario

Plants are pretty much everywhere. From our lawns to city parks and even on the sidewalk! And it’s a good thing as it helps to keep our environment clean and clear. But some of us grow plants because we love gardening and we have a variety of plants in our backyard or lawn. But gardening is not an easy hobby as there are a lot of problems that a person has to face. From insects to soil fertility, the list of issues is long and so is the list of its solutions. But there is one problem that seems to have no end, and it is weeds!

Weeds In A Field

Weeds in a field . (Photo Credit : Kodak EasyShare Z612 / Public Domain Pictures)

If you ever observe the gardens around you or your own lawn, you may have come across plants which seem as if they are out of place. These unwanted plants that you may have noticed are ‘weeds’. Yes, ‘weed’ is not a specific plant but rather it is a term used by humans to describe plants that are ‘growing in the wrong place’.

Why are weeds so persistent?

These things can grow in almost any environment ranging from favorable places (such as farms, nursery, and gardens) to unfavorable ones (structures like pillars and walls). Their growth is a problem for farmers/gardeners as weeds use up a lot of nutrition and affect the plants around them. It also affects the quality of harvested crops. To make matters worse, some weeds produce toxic substances, which not only have an effect on surrounding plants but can also affect the soil quality.

Seed dispersed by air, water, fruit

Ways of seed dispersal

One of the major factors behind their high growth rate is an abundant seed production and their high rate of survival. They are developed according to the environment in which they are being dispersed (for example – by air, water or fruits). Certain weeds also have the advantage of vegetative reproduction that allows them to grow an entirely new plant from the fragment of the parent plant with the only similarity being their genetic makeup. Some even have the ability to hybridize.

In case of hybridization, the crossing takes place between two genetically different plants. The third plant created has a different set of traits. This helps them achieve genetic variability. Such variability could lead to the development of mechanisms to protect themselves from control measures such as herbicides.


Many of the weeds adjust to the environment which helps them to not just spread but also survive. Some of the types develop waxy layers on their leaves which act as a defense mechanism. This helps them to stay protected against any chemical treatment and don’t let the chemicals penetrate. These stubborn plants even grow in areas with low fertile soil. They also develop foul odor and taste which prevents the animals from consuming them. The ability to produce toxic material also helps the cause of keeping animals at bay.


If you think that, ‘Why can’t I simply apply herbicides and be done with them?’ It probably isn’t the best of ideas as the weeds could be ‘biologically similar’ to the plants itself. In such a situation the herbicide will end up destroying weeds and your plants. Even after applying herbicides, the seeds that have already been dispersed by the weeds have a great chance of germinating. So the overall effect of applying herbicides would be worse on the plants than on the weeds!

You could cut them in half, apply poisonous chemicals and not give any nutrition and they would still happily keep growing. All of this makes weeds a long-lasting group of plants that are highly competitive!


  1. Cal State Monterey Bay
  2. Pennsylvania State University
  3. Iowa State University Department of Agronomy
  4. Biology LibreTexts

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