Aliens

Exotic animals and plants are crisscrossing the globe as never before. Many of these unwelcome species have found their way to the Chicago area and are wreaking havoc on our local ecosystem.

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NAME: Purple loosestrife (Lythrum salicaria)
ORIGIN: Europe and Asia
DATE INTRODUCED: Early 1800s; arrived in Illinois in the 1940s or 1950s
HOW IT GOT HERE: brought as an ornamental plant and herb; the seeds also spread through the ballast of ships and sheep’s wool.

This magenta-flowered perennial may look pretty, but it’s “a real scary weed,” says the Field’s Ross. Capable of growing to heights of three to seven feet, purple loosestrife aggressively overwhelms local wetlands, crowding out native grasses and destroying the habitats for some amphibians and waterfowl. “You lose the birds, you lose the bugs, you lose the native wetland plants,” says Ross. “It becomes a big wet area of purple loosestrife.” Nationwide, purple loose-strife spreads across an estimated one million acres of wetlands each year, mainly because it produces thousands, sometimes millions, of seeds annually and can even reproduce from roots and broken stems.

THE FIGHT: Purple loosestrife has no natural predators here, so biologists have imported three types of leaf- and root-eating beetles and a flower-eating weevil from Europe and Asia to devour this menace.

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