ST. LAWRENCE EASTERN LAKE ONTARIO PARTNERSHIP FOR REGIONAL INVASIVE SPECIES MANAGEMENT
Himalayan balsam (Impatiens glandulifera), also known as policeman’s helmet, is an annual herbaceous plant that grows 3–10 ft in height and threatens the biodiversity of riparian and wetland/moist areas. It is native to western Himalayas and was initially introduced to North America as a garden ornamental.
Himalayan balsam forms dense monocultures that outcompete native plants for space, light, nutrients, and pollinators, reducing overall biodiversity. As an annual species, it dies back each year, leaving bare soil that can increase erosion along riverbanks. A single plant can produce more than 800 seeds that spread easily by wind, animals, and human activity, and its dried seed pods can burst on contact, forcefully ejecting seeds and accelerating its spread.
Species occurrences in the SLELO PRISM are documented in Jefferson, Lewis, and Oneida counties, where the plant occupies disturbed, nutrient‑rich soils in riparian zones, wet meadows, and moist woodland habitats. It does not tolerate drought, thrives in full sun, and can persist in partial shade. These habitat preferences shape where the species is most likely to establish and spread, especially in areas with consistent moisture and recent soil disturbance.
Leaves are simple, lanceolate to lance-ovate shaped, toothed (serrate), and around 6 inches long with acuminate tips. They are arranged opposite or whorled.
Flowers occur from June to October. They are pink, irregular, solitary flowers and appear on axillary stalks.
Fruits are five chambered capsules that, when mature, explode expelling seeds forcefully. Each plant produces about 800 seeds.
Two native species in the genus Impatiens occur in the SLELO PRISM region. These are spotted jewelweed/touch-me-not (Impatiens capensis) and pale jewelweed/touch-me-not (Impatiens pallida). Like Himalayan balsam, these species prefer moist/wetland habitats.
Spotted Jewelweed/Touch-Me-Not (Impatiens capensis).
Leaves: Leaves are up to 3 inches long and 1½ inches wide, hairless, oval to egg-shaped with widely spaced teeth and stalks up to 1 inch long.
Flowers: Groups of 1 to 3 flowers are found on branching stems. The flowers are tube or funnel shaped, about 1 inch long and ½ to ¾ inch wide, with a long narrow spur at the back that curls back under the tube. Color is variable (orange, white, yellow), but typically orange with varied amounts of red spots inside the flower that are sometimes absent. Flowering occurs July to September.
Fruits: Fruit is a slender pod about 1 inch long that pops open, releasing the seeds, at the slightest touch.
Pale Jewelweed/Touch-Me-Not (Impatiens pallida)
Leaves: Leaves are up to 5 inches long and 3 inches wide, hairless, toothed, oval to egg-shaped, on stalks up to 2 inches long.
Flowers: Groups of 1 to 3 flowers are found on branching stems. The flowers are tube or funnel shaped, about 1 to 1½ inches long and nearly as wide as long, with a narrow spur at the back that bends down. Color is yellow with reddish spots, often near the base of the lower lobes, but sometimes absent. Flowering occurs July to September.
Fruits/Seeds: Fruit is a slender pod about 1 inch long that pops open, releasing the seeds, at the slightest touch.
Management of Himalayan balsam (Impatiens glandulifera) focuses on stopping seed dispersal, using methods such as early‑season hand‑pulling, cutting plants below the lowest node, or applying glyphosate in jurisdictions where it is allowed. Its reliance on water‑borne seed movement makes whole‑catchment control essential.
For best results, a combination of the methods outlined below, tailored to the specific site, should be used.
Prevention is the first and preferred approach when managing any invasive species. Being aware of and able to identify invasive species is crucial for successful prevention.
Monitor and manage the plants in the spring and early summer, before seed set. Seeds begin to appear in September. Maintain high caution if working with this plant after it has seeds as the pods can explode if touched, spreading the seeds.
Clean your shoes and equipment after entering infested areas.
Hand-pulling and mechanical removal may be used to control populations.
Chemical Treatment: The use of herbicides in water is regulated; always consult state and local regulations for required permits.
Biological Control:
Take a clear, close-up photo, note the location (GPS coordinates are best), and report observations to NYiMapInvasives or directly to the SLELO PRISM’s Terrestrial Restoration and Resiliency Coordinator, Robert Smih, at robert.l.smith@tnc.org.
Education and stewardship are the most effective ways to prevent the spread and introduction of invasive species. You can help by joining our Volunteer Surveillance Network. Participants learn how to recognize, report, and monitor for priority terrestrial and aquatic species.