Published July 6, 2024

Photo courtesy

By Pooja Sainarayan

Local Journalism Initiative

Invasive plants and weeds are often used interchangeably, but generally speaking, weeds refer to plants growing where they are not welcome. Weeds can be local or non-local, invasive or non-invasive, and competitive or easy going. However, weeds tend to share certain properties in which they can gain advantage over desirable plants. First, they can reproduce in many way – sexually by seed and asexually by rhizomes. Second, certain weeds can block the sun from other plants by leafing out sooner than slower growers. They can also retain their leaves for a longer time during fall, allowing for a longer photosynthesis period and ultimately increasing their survival. As a result, weeds have populated areas undergoing extreme conditions such as draughts and have come on top as survivors. Apart from their top-notch survival skills that can harm the reproduction of other plant species, can our local weeds serve other purposes?

Weeds can give us a lot of information about soil, as all plants have specific environmental conditions, including soil preferences in order to thrive. For instance, the nitrogen content and whether the soil is too compacted or eroded. Identifying weeds that give hints on these possible issues can help us make the needed changes such as tilling or adding organic matter to our gardens. An example is weeds with deep taproots, such as dandelions and burdocks can be an indicator of compacted soil that lacks air, water and nutrients. On the other hand, weeds are the ecosystems way of correcting the soil to achieve more balance. Dandelions and burdocks have deep and strong roots that also help break up the compacted soil. Similarly, weeds can also be an indicator of good soil. In the case of common groundsel, knapweed, lambsquarters and fiddleheads that are all common weeds of Quebec, signal nutrient-rich and fertile soil.

Apart from providing hints of soil conditions, some weeds have played crucial ecological roles. The milkweeds are a prime example of such weeds. In Quebec, there are four native species – Common milkweed, Swamp milkweed, Poke milkweed (relatively uncommon), and the Butterfly milkweed (endangered species in Quebec). Milkweeds are perennials that carry flowers grouped in umbels. They are called milkweeds because of the milky white sap that leaks when the plant is injured, which may cause an allergic reaction in some people. The nectar of milkweed attracts many pollinating animals such as butterflies, hummingbirds, bees and wasps. Monarch butterflies feed exclusively on milkweed, being the only host plant for this butterfly species. The issue is, despite the importance of native milkweeds, these plants are often mistaken for regular weeds and wiped out causing harm to pollinators and declines in the monarch butterfly populations. In addition, milkweed has been used by the First Nations as food, and to make rope. The common milkweed has made a comeback because of the properties of its fiber, which is made by the silky hairs of its seeds. It is used primarily in thermal insulation, stuffing for quilts and pillow and even as an absorbent material in oil spills.

Other weeds such as dandelions and purslane offer several health benefits to humans. In French, the word dandelion translates to “pissenlit” which translates in English to “pee in bed”. This name comes from the strong diuretic properties of the dandelion leaves. The dandelion plant is edible and has been used throughout history to treat several conditions such as digestive ailments, joint pain and fever, although the evidence of efficacy requires more research. The dandelion leaves are highly nutritious, providing beta-carotene and vitamins C and K. The roots contain inulin, a prebiotic fiber that nourishes the good-gut bacteria. So, skip the weed killer and rid your lawn of dandelions by harvesting them! Similarly, purslane, also known as portulaca is an edible weed. It is known to contain ten times the omega 3 fatty acids found in spinach. It can be served raw in salads where it tastes like pea shoots, or it can be steamed where it tastes like spinach. Of note, beware of toxic imitators such as euphorbias that often grow close by. Euphorbias release a milky sap when its thick stem is broken, providing an easy method of identification.

To conclude, weeds can be detrimental to the garden and in some cases even toxic to humans. On the other hand, they can provide many benefits to pollinators and human health, meriting more respect than they get. It may just be worth it to research our garden weeds in more detail to learn about their possible key roles in our ecosystem and human health.

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