All Canadian Weed Man asks is, ‘give weeds a chance’

Contributed by David Clements, PhD

Dubbed “Canada’s Weed Man” by his peers, Clements is the editor of the Canadian Journal of Plant Science, professor of biology at Trinity Western University and an expert in weed science.

Langley, B.C.—As life awakens this spring, most people will again identify the weed as an enemy. Pigweeds overtake gardens, barbed blackberries overtake large areas of land and horsetails never go away no matter how often they’re pulled. Despite their inconveniences, many “weeds” have beneficial medicinal and industrial uses. In every case, a healthy view of these complex plants can shed light on our interaction with them.

In its natural habitat, a plant can thrive without affecting its surroundings. But take a plant out of its home environment and it develops “weedy” characteristics. The displaced plant can produce a large number of seeds causing out-of-control growth, or it can invade areas with disturbed soil as a biological pollutant that can be difficult to eliminate. Purple Loosestrife, for example, is scarcely noticed in its native Europe. Yet the same plant in North America is a purple plague infesting our wetlands.

In B.C., an estimated $50 million is lost annually to weed problems. Weeds with thorns, such as blackberries or gorse represent serious human health threats and giant hogweed causes significant contact dermatitis problems. In Alberta, the ox-eye daisy is jepordizing an over $600 million/year industry by infecting pastures grazed by cattle and souring milk intended to be sold commercially.

Under the weight of these ecological and economic pressures, the Canadian government has instituted plans to combat weed related issues. The Federal Seeds Act monitors the import and export of seeds while the Provincial Weeds Act controls invasive species growth.

But we need to be careful about labeling plants as “bad.” St. John’s Wort, while toxic to livestock, can be used to treat depression, milkweed has been investigated for the production of latex and others help clean up sites contaminated with heavy metals and toxins.

Indeed, most weed problems are caused by humans. The department of transportation first planted scotch broom, the brilliant yellow bush along highways that produces thousands of seeds that can survive in soil for decades. Even nurseries confuse the invasive ox-eye daisy with the ornamental Shasta daisy, mistakenly selling the weed instead of the flower.

If “wildflower” seeds ordered over the internet are planted without doing research, new weeds can thrive in a place where they’ve never existed before. A neighbour of mine had been given a plant by a friend who called it a ‘rare Himalayan orchid.’ To her horror, she found it was an invasive weed of streamside areas—Himalayan balsam. This weed from Asia is rapidly increasing in B.C. and has already caused havoc around waterways in Great Britain and Eastern Europe.

Ralph Waldo Emerson said that a weed is simply “a plant whose virtues have yet to be discovered.” If we consider a weed to be “a plant out of place,” then we should afford them the opportunity to define where their place is. If weeds can benefit us, then perhaps they are worth a second look.

Trinity Western University, located in Langley, B.C., is a not-for-profit Christian liberal arts university enrolling over 3,500 students this year. With a broad based, liberal arts and sciences curriculum, the University offers undergraduate degrees in 38 major areas of study ranging from business, education and computer science to biology and nursing, and 13 other graduate degrees including counselling psychology, theology and administrative leadership.

Last Updated: 2015-07-16
Author: Keela Keeping