Biodiversity Bullies

The enjoyable tradition of sharing plants and seeds across borders has led to the spread of invasive plants that are sold at local nursery and landscape centres as exotic annuals and perennials.

Invasive plants are the second greatest threat to biodiversity after habitat loss. Due to limited regulation and increased imports, BC gardeners can help prevent their introduction and spread.

Why are invasive plants a problem?

Invasive plants harm the environment by aggressively out-competing native plants. When these globe-trotting plants arrive in BC’s nurseries and greenhouses, they typically leave their natural pests and predators behind, giving them a competitive advantage over local species.

Having no predators, invasive plants can direct more energy into growing new shoots, spreading thousands of seeds, and capitalizing on open ground.

People, livestock and pets can be harmed by invasive plants. For example, giant hogweed (Heracleum mantegazzianum) can cause severe and permanent dermatitis from toxic oils in its hairs and sap. It is so dangerous that WorkSafeBC has developed a video on safe disposal.

Invasive plants have adverse effects on the economy. Property and crop values drop while costs for treating infestations rise. Invasive plants also impede recreation by making trails impassable and damaging fishing streams.

The list of invasive plants in BC grows yearly. Some of the most “unwanted” plants include: common periwinkle (Vinca minor), English ivy (Hedera helix), Scotch broom (Cytisus scoparius), Dalmation toadfl ax (Linaria dalmatica), Japanese knotweed (Fallopia japonica), Himalayan blackberry (Rubus ulmifolius or R. discolor), purple loosestrife (Lythrum salicaria), giant hogweed (Heracleum mantegazzianum), and oxeye daisy (Leucanthemum vulgare).

Be informed

• Before purchasing, ask your nursery if plants are “fast spreaders” or “vigorous self-seeders”; usually these are signs of an invasive plant.

• Wildflower and birdseed mixtures can contain invasive plants. Buy the components separately and mix yourself to be sure.

• For better options: www.greatplant picks.org

Five ways you can help

1. Avoid walking/driving/riding through invasive plant infestations.

2. Remove seed and plant parts from clothing, pets, vehicles and equipment, and dispose at the local refuse site. Inform the landfi ll operator that you have invasive plants and not regular yard waste.

3. Don’t allow invasive plants to fruit or set seed.

4. Avoid picking plants from roadsides; many wildfl owers are invasive species.

5. Learn how to identify and report invasive plants in your community and pass these insights on to your neighbours.