History and Impact
Policeman's helmet, also known as Himalayan balsam, thrives in moist areas and riparian zones. Although sometimes sold as an ornamental, this native of Asia has been added to the Washington State Noxious Weed list due to its invasive nature. In Britain, where the climate is similar to the Pacific Northwest, this plant is considered extremely invasive and is one of the "top 20" non-native weeds. As a Class B noxious weed, policeman's helmet control is required in King County.

Biology and Morphology
Policeman's helmet is an annual that germinates from February through March and flowers from June to October. Growing up to 10 feet tall, the upright stems are hollow with a purple or reddish tinge; leaves are oblong to egg-shaped, with serrated edges, with white, pink or purple flowers resembling an old-fashioned English policeman's helmet. A single plant can produce up to 800 seeds, which are viable for 18 months or more and can even germinate under water. Since the plant often grows along streams and ditches, seeds spread quickly downstream. When touched, the mature seedpods split and eject seeds up to 20 feet. This trait has earned the Impatiens family the name of "touch me not."

Policeman's helmet photos - click thumbnail for larger image

For information on policeman's helmet identification and control, please download our policeman's helmet weed alert (1.58 MB Acrobat file).

For detailed information on managing policeman's helmet in King County, please read the policeman's helmet best management practices (209 KB Acrobat file).

For more information about policeman's helmet, please see the written findings of the WA State Noxious Weed Control Board.

If you find policeman's helmet in King County, please notify us through our online infestation form.

To find out where we have records of this weed in King County, use our interactive noxious weed map and search for policeman's helmet.