Description:
Garden loosestrife is an erect rhizomatous perennial that may attain a height of one meter or more. Both the stems and the leaves are softly hairy. Lance-shaped leaves, 8-12 cm long, occur on the stem in an opposite or whorled arrangement. The leaves are dotted with black or orange glands. The yellow, primrose-like flowers occur in a cluster at the top of the plant. Each flower has five petals and a calyx with reddish-brown margins. The fruit is a dry capsule.

• Mechanical: Garden loosestrife has been covered with black plastic at least one site on Lake Sammamish. This may be effective on very small populations or serve as a suppression tool where herbicides are not desired. Other alternatives have not been studied. Since the species has extensive rhizomes, handpulling or digging would be limited to very small infestations.
• Biological: No biological control agents are presently known. No research is currently being conducted.
• Herbicide: Response to herbicides is not currently known. Applications of Rodeo® to the Lake Sammamish populations will be monitored for effectiveness. Refer to the State Noxious Weed Control Board site

For More Information:
Detailed information about Garden Loosestrife is available at the Washington State Noxious Weed Control Board Web Site.