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December 04, 2016
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Plants behaving badly; Love that ‘ornamental’ plant? Not so fast, please

Purple loosestrife was brought over from Europe in the early 1800s as an ornamental plant and as a medicinal herb. Loosestrife is now found in all contiguous states (except Florida) and in all Canadian provinces. Purple Loosestrife has stiff, four-sided stems; linear shaped leaves with smooth edges; and rose-purple-colored flowers that form in a long spike.

Myers stresses that river valleys are potential hotbeds for invasive species because they provide conditions ideal for invasive spread. Water, wind, soil, birds, animals and humans all do their part to disseminate seeds, spores and roots. But, Myers says, humans are by far the worst culprits. Not only are they more numerous than other agents, but they also travel farther and faster and cause more environmental disturbance wherever they go. Disturbed soil is the best medium for invasive plants.


Prevention is the first line of defense in any management program. Invasive species should not be planted knowingly. Surprisingly, some invaders are available from nurseries—Japanese barberry, purple loosestrife and Japanese honeysuckle among them. To guard against deliberate planting, consumers should be able to identify invaders by both name and appearance; additionally, Myers urges consumers to obtain their plants from native plant providers, plant swaps and nurseries that grow their plants from seeds or cuttings.


Methods for management and eradication of invaders vary in accordance with the individual species’ methods of propagation. Options include manual removal (hand weeding), machine removal (mowing, weed whacking), herbicides, grazing (sheep and goats will eat anything edible down to and including roots), burning, and biological attack by natural enemies of the invader (insects, bacteria and fungi). Each method has both advantages and drawbacks, and no one method is safe and effective against all invaders and under all circumstances. There is one more option, to be used either as a last resort and/or a best defense—harvesting. Each plant species, however antisocial its behavior, has attributes that make it useful. Even Japanese knotweed, one of the most tenacious and pervasive invaders, has its uses. The plant’s stalks are used in papermaking. Honey made from its blossoms is considered a delicacy. The plant’s botanical properties are currently being used in the treatment of Lyme Disease. And bakers may find that the plant’s young stalks make a delicious dessert (see Japanese Knotweed Squares recipe).