Bureau of Land Management Learning Landscapes

What's Wrong With This Picture?

Invasive Weeds: A Growing Pain

Many weeds have pretty flowers but they are a growing pain. They crowd out native plants, harm animal habitats and increase erosion.

Purple Loosestrife is found in the eastern and western U.S. An invasive wild plant, hybridized non-invasive varieties are sometimes available to gardners.

Spotted Knapweed is found in eastern and western U.S. An aggressive competitor, first spotted in Montana in 1920, it has spread widely on rangelands. One plant can produce 1,000 seeds. These seeds can lay dormant for 8 years.

Leafy Spurge is found throughout most of the northern half of the U.S. Its powerful root system can reach 25 feet deep.

Yellow Starthistle is found in the extreme western U.S.; found also in local areas scattered throughout the rest of the U.S.

Dalmatian Toadflax is scattered throughout northern and western U.S.

Garlic mustard, a shade tolerant plant, establishes thick stands in forests where it threatens native spring wildflowers from Canada to Virginia and west to Kansas and Nebraska.

From the Poster Front:

Oriental bittersweet, an aggressive threat in the Eastern United States, is a twining vine that can smother trees and saplings.

Water hyacinth clogs aquatic ecosystems in the South forming dense mats which block sunlight and prohibit boat traffic.

Melaleuca, an Australian tree, is spreading out of control in the Florida Everglades.