Purple Loosestrife

Lythrum salicaria

A plant which is "deadly" -- not to people but to New England's native wetland plants -- is purple loosestrife or Lythrum salicaria. This exotic species was introduced to New England from Europe in the 1800's; its seeds crossed the Atlantic in three ways: in European soil which was used as ballast in ships then dumped along New England's coasts, in the wool of sheep, and in the pockets of immigrants who wanted to plant loosestrife in their gardens. Purple loosestrife is a perennial flowering plant which now covers many acres of wetlands in New England. It spread rapidly because it tolerates many soil types, water levels, and climate variations; it has almost no diseases or predators in America, and it reproduces via both seeds and new growth from pieces of the plant's roots or lower stems. Each mature plant annually produces over 2 million tiny seeds which are easily transported by wind, water, and wildlife when they are released from their seed capsules in the fall and winter. Seeds may germinate the following spring or remain dormant for a few years before sprouting.

Between June and September, wet meadows, marshes, pond sides, and ditches in southeastern Canada and the northeastern United States blaze with 12-inch spikes of purplish-pink flowers atop the 2 to 8-foot erect stems of purple loosestrife. Loosestrife's stems are angular and become woody with age. It's leaves are long, narrow, toothless, and usually opposite each other beneath the circular clusters of 3/4- inch-wide flowers with 4 to 6 wrinkled petals each. Unfortunately, the roots of purple loosestrife form dense mats which crowd out cattails, sedges, and other native plants that provide food and shelter for many forms of wildlife. As purple loosestrife takes over and plant diversity falls, wetlands support fewer species of insects, birds, amphibians, reptiles, and mammals. Even fish are crowded out when purple loosestrife's roots clog the waterways in the marshes where fish normally come in to spawn. So, don't judge a plant by its flower; although it is nice to look at, purple loosestrife is an undesirable alien in the ecology of New England.

by Darlene Smalley


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