The most basic definition of a weed is a plant that is growing where it is not wanted. As with many things, the definition can become a little more complicated. A weed can cause harm to people, livestock, the economy or the environment rather than just being an ‘unwanted’ plant. Weeds share common traits that enable them to earn that title, including:
- the large numbers of seeds produced
- can grow quickly in comparison to non-weedy species
- rapid reproduction
- are able to survive in many environments, especially those that are disturbed
- can be spread easily through vegetative means (re-grow from samll sections of the plant), or through a plant’s berries being eaten by wildlife and the seeds being deposited elsewhere.
- survive easily in an area with an extreame climate
A plant can be a weed for several reasons. Firstly, there are weeds of agriculture/food production. These weeds compete with animal food or horticultural crops for light, nutrients and water, reducing the crop yield. Other plants are toxic to livestock and even to humans, which can also cause serious problems.
Environmental weeds occur mainly where a natural ecosystem has been disturbed, allowing the weedy plants to get a foothold in that area. Such plants in this environment negatively affect the survival of native Australian flaura and fauna, which is worthy of protection in its own right. On a similar note, weeds can be an issue in disturbed areas of a built up city or town-how often do you see weeds poking up through cracks in a pavement or abandoned block of land?
Weeds can be an aestetic problem in a back gardens, public parks, sports fields or in any built up space. Here unwanted plants can simply look ugly, impact the way a sport is played on grass (like the greens for playing golf), or just look out of place. Some plants can cause damage to property, so its always worth choosing new plants wisely!
Finally, weeds can be a home to a number of pests and diseases that can go on to infect or damage other plants in the area in question. Unless the weeds are controlled in this situation, a lot of money, time and energy will be wasted on trying to control a problem that will be solved more easily by removing the source of the issue, i.e. the weeds.
In Australia, most weeds are those that have been introduced from elsewhere in the world. These plants have come into the country for many reasons:
- a reminder of ‘home’
- they look great in a garden situation
- have edible or medicinal properties
- have any number of other practical uses
Some native Australian plants can also be weeds. In this case, such plants grow outside their natural ranges and begin to take over in the area into which they have been introduced.
References
- What is a weed?, https://www.aabr.org.au/learn/what-is-a-weed/, accessed 12/05/2022
- Home Gardeners https://www.dpi.nsw.gov.au/biosecurity/weeds/home-gardeners, accessed 29/05/2022
- Richardson, F.J., Richardson, R.G., Shepard, R.C.H., Weeds of the South-East an Identification Guide for Australia, third edition, 2016, Victoria, Australia
- All photos are my own, taken in my local area