Policeman's helmet

General Information

Policeman's helmet or Himalayan balsam (Impatiens glandulifera) is a tall (1 to 2 m) annual plant with showy pink flowers that are very attractive to bees. It has hollow stems with long, slender leaves and dies back each fall.

Growth Habit

Policeman’s helmet is tolerant of many soil types but tends to grow in moist soils, including along the edges of streams and wetlands. It can grow in full sun or in shade. Reproduction can occur vegetatively, but the most effective means of reproduction is the prolific seed production and effective dispersion. Seeds are produced in tubular pods with twisted ends. When pods are mature, they explode, launching the seeds up to 5 metres from the plant. Seeds can float along streams and are able to survive in the soil for up to 1.5 years. As it grows very tall and dense, it can displace other plants. Also, when it dies back each fall, it leaves bare soil which is then prone to erosion. This is an aggressive invasive plant of wetlands and streams.

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Management

Policeman’s helmet is relatively easy to control if it is pulled by the roots. The seeds last in the soil for up to 18 months, so it is possible to control an infestation with only 2 to 3 manual removals. Pulling the roots from the soil is a less appealing option when the plants are growing adjacent to streams as disturbance to the moist soil will likely cause streambank erosion and possible alteration to the stream course.

Alternatives for planting:

hardhack (Spirea douglasii)
red-osier dogwood (Cornus stolonifera)
fireweed (Epilobium angustifolium)
western columbine (Aquilegia formosa)
tiger lily (Lilium columbianum) – all native species that provide habitat for native wildlife.

Identification

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."

Sea to Sky Invasive Species Council