Balfour's touch-me-not (Impatiens balfourii)

Synonyms: Impatiens mathildae

Common Names: Kashmir balsam, poor man's orchid, Balfour's balsam

Description:

Balfour's touch-me-not (Impatiens balfourii) is a fast-seeding annual from the western Himalayas, grown in gardens for its showy pink-and-white flowers [1][5]. It escapes cultivation and self-sows into moist, shady ground ? stream edges, woodland borders, and disturbed areas ? where it competes with native plants [2][5]. MISIN tracks it because it is an early-stage invader in North America that spreads quickly by flinging its seeds, making it a good target to catch before it becomes widespread [2][4].

Habit:

Balfour's touch-me-not is a slender annual, usually 1 to 2.5 feet tall, with upright, smooth, translucent pale-green stems that snap easily [2]. Its leaves are oval with a long pointed tip and toothed edges [2]. The flowers are its most eye-catching feature: two-tone pink and white, with a hooded upper part, lower lips, and a long thin spur curving off the back, carried a few to several together on slender upright stalks [2][3]. It is easiest to identify from mid-summer into fall, when it is in flower; later in the season look for the plump green seed pods, which burst and curl when touched ? the trait behind the name "touch-me-not" [2]. It grows in moist, shaded places, often near gardens it has escaped from [2][5].

At-a-glance cues:

1. Two-tone pink-and-white flowers with a hooded top and a long spur at the back [2][3]
2. Slender, smooth, translucent pale-green stems, 1 to 2.5 feet tall [2]
3. Oval leaves with long pointed tips and toothed edges [2]
4. Ripe seed pods burst and coil when touched, flinging seeds [2]

Leaves:

1. Arrangement: alternate along the stem [2]
2. Shape: simple, oval to oblong with a long, drawn-out pointed tip [2]
3. Margin: toothed (serrated) [2]
4. Surface: smooth, thin-textured [2]

Stems:

1. Habit: upright herbaceous annual, 1 to 2.5 feet tall, simple or branched [2]
2. Texture: smooth, translucent, pale green, and easily snapped (not woody) [2]
3. Roots: shallow and fibrous, so plants pull up easily [2]

Flowers:

1. Color: two-tone ? white to pale upper hood with rosy pink-to-purple lower lips [2][3]
2. Shape: the petals form a hood and lower lips, with a long, slender spur curving off the back [2]
3. Arrangement: a few to several flowers (about 4 to 8) on slender, upright stalks [2]
4. Bloom time: mid-summer into fall [3]

Fruit and seeds:

1. Fruit: a slender capsule about 1 to 1.5 inches (2 to 4 cm) long [2]
2. When ripe, the capsule splits and the sides coil suddenly, flinging the seeds away when touched or brushed [2]
3. Seeds are small, about 1/8 inch (2.5 to 3 mm), and stay viable in the soil for roughly 18 months [2]

Habitat:

Balfour's touch-me-not is native to the western Himalayas [1]. It was introduced to gardens as an ornamental in the early 1900s and has since escaped into the wild [1]. In North America it is not native; it has naturalized in scattered spots, mostly in the West and upper Midwest [5]. It favors moist, partly shaded ground and turns up in forest understories and edges, wetlands, grasslands, and along streams and ditches, as well as in disturbed areas and old garden sites [2][5].

Reproduction:

Balfour's touch-me-not is an annual ? it lives a single year and spreads only by seed [2]. Its ripe pods burst at the lightest touch, flinging seeds a few feet from the parent plant, so a patch creeps outward and a single garden plant can seed a whole bed [2]. Seeds also travel farther in soil, on tools and boots, and along streams and ditches, which is why it often shows up in moist, low ground [2]. People move it mainly by planting it as an ornamental and letting it escape [1][3]. It self-sows heavily, and its seeds stay alive in the soil for about 18 months [2].

For control timing: because it lives only one year and makes no roots that resprout, the goal is simply to stop it from setting seed ? pull or cut the plants while they are flowering, before the pods ripen and start flinging seed [2][3].

Impact and Damage:

In a garden, Balfour's touch-me-not rarely stays where it is planted ? it self-sows freely and pops up in beds and borders, and it readily jumps the fence into nearby moist ground [2].

In natural areas it forms patches in moist, shady spots ? streamsides, wetland edges, and woodland floors ? where it competes with native plants for space, light, and pollinators [2]. Deer tend to avoid eating it, so where deer are heavy they may graze the surrounding native plants instead, giving this plant an added edge [2]. Compared with its notorious relative Himalayan balsam, Balfour's touch-me-not is considered a less aggressive invader and is still in the earlier stages of spreading in North America ? which is exactly why catching it early matters [4][1].

Similar species:

Balfour's touch-me-not is most easily confused with other members of the touch-me-not family, which all share its explosive seed pods.

Himalayan balsam (Impatiens glandulifera), also called policeman's helmet, is a much more aggressive invasive relative. It is far taller ? up to about 10 feet ? with larger pink-to-purple flowers, while Balfour's touch-me-not stays slender at 1 to 2.5 feet and has smaller two-tone pink-and-white flowers [3].

Spotted jewelweed (Impatiens capensis) is a native touch-me-not with the same kind of spurred flowers and bursting pods, but its flowers are orange, not pink and white [3].

Pale jewelweed (Impatiens pallida) is another native touch-me-not, told apart by its yellow flowers [3].

Monitoring and rapid response:

Signs to watch for:

1. Slender annual plants 1 to 2.5 feet tall with two-tone pink-and-white spurred flowers, mid-summer into fall [2][3]
2. Moist, shady spots ? streamsides, wetland edges, woodland floors, or near gardens it has escaped [2][5]
3. Green seed pods that burst and curl when touched [2]

What you can do:

1. Because it is an annual that spreads only by seed, the key is to stop it before the pods ripen: pull plants by hand ? they come up easily with their shallow roots ? or cut or mow them while they are flowering [2][3]
2. Handle ripening plants gently; touching mature pods scatters seed, so bag flowering and seeding plants before disturbing them [2]
3. Bag and trash the plants rather than composting or dumping them, since the seeds can sprout elsewhere [2]
4. Return for the next season or two to pull seedlings from seed already in the soil, until the patch stops coming back [2]
5. Natural area crews can sweep streamsides and trail edges, removing outlying plants before seed set and revisiting for a few years to draw down the seed bank [2]

When to call a professional:

1. Large, well-established stands, especially along streams or in wetlands where access is difficult [2]
2. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. Plants of the World Online (POWO), Royal Botanic Gardens, Kew. Impatiens balfourii Hook.f. powo.science.kew.org
2. Wisconsin Department of Natural Resources. Balfour's touch-me-not (Impatiens balfourii). dnr.wisconsin.gov
3. Tualatin Soil and Water Conservation District. Balfour's Balsam (Impatiens balfourii). tualatinswcd.org
4. Ugoletti P, Stout JC, Jones MGK. "Ecophysiological traits of invasive and non-invasive introduced Impatiens species." Biology & Environment: Proceedings of the Royal Irish Academy. semanticscholar.org
5. USDA NRCS PLANTS Database. Impatiens balfourii Hook.f. plants.usda.gov

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