Impatiens glandulifera, widely recognized as Himalayan Balsam, is an annual flowering plant originating from the Himalayan mountains. It was introduced to Europe and other parts of the world in the 19th century as an ornamental garden plant due to its striking appearance. Its tall stature and attractive pink to purple, orchid-like flowers made it a popular addition to gardens.
Recognizing Impatiens glandulifera
Impatiens glandulifera has several distinct physical characteristics. The plant features hollow, smooth stems that can reach heights of 1 to 3 meters (3.3 to 9.8 feet) and often display a purple or reddish tinge. Its lance-shaped leaves are serrated along the edges and grow in whorls of three or opposite pairs, ranging from 6 to 25 cm (2.4 to 9.8 inches) in length.
The flowers, which bloom from mid to late summer, are irregular in shape, about 2.5 to 4 cm (1 to 1.6 inches) long, and appear in shades of pink to purple, occasionally white. They feature a short, curved nectar spur at the base. Following flowering, the plant produces seed capsules, 1.5 to 3.5 cm (0.6 to 1.4 inches) long, which explosively open when mature or disturbed, dispersing up to 16 seeds per capsule as far as 5 meters (16.4 feet) from the parent plant. This explosive dispersal mechanism earns it the name “Touch-Me-Not.”
Ecological Impact
Impatiens glandulifera is problematic due to its aggressive growth and ability to form dense, single-species stands. It rapidly outcompetes native vegetation for sunlight, water, and nutrients, reducing local biodiversity. This prolific nectar producer also draws pollinators away from native plant species, hindering their reproduction and establishment.
The plant’s annual life cycle increases riverbank erosion. While it provides some soil stability during its growing season, its shallow root system provides limited support. When the plant dies back in winter, it leaves large areas of bare soil, particularly along waterways, making these areas vulnerable to erosion and altering riparian hydrology. This influx of sediment and organic matter into water bodies reduces water quality and affects aquatic ecosystems.
Management Strategies
Effective control of Impatiens glandulifera often involves non-chemical approaches, with timing being important. Manual pulling is a highly effective method for smaller infestations, due to its weak, shallow root system, making it easy to remove from moist soil. This should be done in the spring and early summer, from May to August, before the plants produce seeds. If plants are pulled after seed pods have formed, pods must be carefully removed into a garbage bag to prevent accidental seed dispersal.
Cutting or mowing is another viable option, particularly for larger stands. To prevent regrowth, the stem must be cut below the first node, close to the ground. Like manual pulling, cutting should occur before the plants set seed, in early summer. Regardless of the method, consistent, repeated efforts over several seasons are needed, as seeds can remain viable in the soil for about two years. Proper disposal of plant material, such as composting or bagging, is important to prevent further spread.