June Invasive Weed of the Month: Policeman’s Helmet

Policeman’s helmet has showy flowers which led to its introduction as an ornamental plant. (Photo: S. Leininger)

Policeman’s helmet (Impatiens glandulifera) is an invasive annual which threatens streams and rivers throughout the Pacific Northwest. It is a Class B invasive weed in Oregon. This means that it is a weed of economic importance. It is also regionally abundant, but may have limited distribution in some counties. Policeman’s helmet has been identified and treated in Clackamas County, so please be on the look out for it.

Native to India, this showy, purple-flowered invasive weed was originally introduced as an ornamental plant. It is highly invasive and forms dense patches wherever it occurs. Look for it in ditches, wetlands, and along waterways.

How Can I Identify Policeman’s Helmet?

Also known as jewelweed or Himalayan balsam, policeman’s helmet grows quickly and produces attractive purple, pink, or white flowers. It naturalized quickly in the Pacific Northwest and now dominates streamside vegetation in many areas.

This aggressive invasive germinates in early spring and can grow up to ten feet tall. The large, upright, reddish stems are hollow and topped with dangling, tubular flowers in showy clusters. Leaves are oblong with serrated edges and a reddish tint.

A dense infestation of mature policeman’s helmet plants

This dense infestation of mature plants will create a bigger problem if not properly managed.

Why Should I Care About Policeman’s Helmet?

Did we mention that it is aggressive? A single plant can produce up to 800 seeds. These seeds are easily carried downstream in flowing water to start a new infestation. Mature seed pods can propel seeds up to 20 feet away! New plants displace native vegetation along stream sides by forming tall, dense stands. These stands shade out competition from other, more beneficial plants.

This aggressive nature leads to a negative impact on our streams and rivers. When the plant dies back in the fall, it leaves streamside soils exposed and unprotected. This causes increased streambank erosion and decreased water quality when water levels in our streams rise in the winter. Additionally, the soil from the exposed banks is deposited on the stream beds, smothering fish eggs and degrading habitat for other aquatic animals.

Policeman’s helmet seeds and exploded pod

Seed pods explode, sending seeds flying everywhere.

How Can I Control It?

Luckily, this invasive weed has a shallow root system and grows in moist soil. Pull it easily by hand, but be sure to remove the entire root! Pulled plants may be composted on site if flowers have not fully formed. Any flowers and immature seed heads should be removed, bagged, and placed in the municipal waste.

Do not pull or move through areas infested with policeman’s helmet when the seed heads are popping! Check and clean clothes, pets, equipment, and vehicles to prevent the spread of this invasive weed.

Report Invasive Weeds!

Have you noticed invasive policeman’s helmet in your area? If so, please report your sightings to the District’s WeedWise program by giving them a call at 503-210-6000. You may also submit your information online to the Oregon Invasive Species hotline. Your help will provide early detection information to the experts working to stop the next invasion before it starts!

Learn More About This Weed

Check out these resources for more information about policeman’s helmet, :

Thank you for your help in identifying and reporting locations of invasive weeds in our community!

Learn How the Clackamas SWCD Can Help You!

Check out our website or follow us on Facebook! We have many resources to help you manage your farm, forest, ranch, nursery, or small urban property. These include our Equipment Rental Program, Horse Keeping and Land Management Program, the Backyard Habitat Certification Program, and our new Septic System Repair and Replacement Grant and Loan Program.

We offer workshops, field days, handouts, and videos to bring you the conservation information you need for your property. We are a non-regulatory public organization and our technical expertise is provided at no cost to Clackamas County residents.


, ,

Clackamas SWCD