People are intrigued by this exotic looking annual because of its pink, helmet-shaped flowers (another common name is “policeman’s helmet”), rapid growth and entertaining mode of explosive seed dispersal.
How does it spread?
Himalayan balsam spreads by seeds. Each plant produces seed capsules that when ripe, explode from the slightest touch, catapulting up the large, black seeds up to 5 m away. The buoyant seeds are easily transported in waterways and deposited on river banks where they rapidly establish. Seeds are known to travel up to 10 km without loss of viability. Pollinators are attracted to the abundant nectar, so seed is readily produced. Plant enthusiasts purchase or dig up Himalayan balsam to put into their gardens resulting in new epicenters and additional spread.
Where would I find it?
Himalayan balsam forms thick, monocultures in moist, shady areas along riverbanks, creeks, sloughs, wetlands and other watercourses. It also occupies open ditches, damp woodlands, railway rights of way, meadows, waste places and roadsides in lowland and steppe zones.
What problems does it cause?
Himalayan balsam’s high reproductive rate, early germination, rapid growth rate, cold hardiness, tolerance of a range of habitats and rich nectar production have allowed it to dominate landscapes. Dense stands that can reach 1.5 to 2 m tall in summer dominate landscapes and outcompete and displace native plants. As it dies back in the fall, bare soil is exposed, increasing the potential for erosion over the winter. Though not commercially available, people who are unaware of its destructive potential contribute to its spread by collecting and spreading seed, or allowing it to grow and produce seed on their property, especially if there are adjacent riparian areas.
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