Purple Loosestrife

When gardeners get together and discuss the Marsh Monster and the Beautiful Killer, they are not talking about the latest horror movie doing the circuit. Chances are they are discussing how to get rid of purple loosestrife, a pesky – but beautiful – plant.

This weed with the tightly clustered pink-purple flowers still grows in many urban gardens, and is still causing trouble in Canada’s wetlands.

“People once believed garden varieties of purple loosestrife didn’t produce seed,” says Cory Lindgren, who oversees Canada’s biocontrol efforts for the invasive non-native. They were wrong. The majority of purple loosestrife infestations are the result of ‘garden escapes.’

“Recent scientific studies have confirmed that loosestrife in gardens is capable of pollen and seed production. These plants can cross-pollinate with other garden varieties, as well as wild loosestrife populations,” says Lindgren.

Like most weeds, purple loosestrife quickly dominates an area and outcompetes native vegetation, resulting in large solid stands of the vexatious plant. And that’s the problem. This drastic change in species composition and decrease in biodiversity affects everything from the nutrient cycling regime to wildlife usage, says Ducks Unlimited, an organization dedicated to the conservation of wetlands for the benefit of waterfowl and other wildlife.

So, what can you plant instead? An environmentally safe alternative to purple loosestrife is spiked gayfeather ­(Liatris), also called blazing star. It is a native perennial with pink, purple or white flowers.

For further information about loosestrife, visit www.ducks.ca/purple

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