
Spotted Jewelweed
Botanical Name:
Impatiens capensis
Class C Noxious Weed
General
- May cause mild to moderate irritation of the digestive track.
- Plants are widespread in certain lowland areas and appear to still be increasing.
- Seedlings of spotted jewelweed can form dense carpets that can compete with native species and are difficult to control.
- Spotted jewelweed is able to hybridize with the Washington native, spurless jewelweed, Impatiens ecornuta.
Identification
- Annual that grows around 2 to 5 feet tall and blooms in late summer with two kinds of flowers–reduced, self-fertilizing flowers and showy, open flowers.
- Flowers are orange and have recurved spurs, are typically spotted, and form capsules after pollination.
- Capsules have the ability to explosively open and propel seeds a short distance.
- Flowers are around 1 inch long with spots (though there is a rare spotless form); having an abrupt and convex taper to recurved spur, spots primarily ventral, coarse and dense.
- Flowers are typically orange and have red to orange colored spots.
- Rarely flower color may vary and the petals can be white, cream or pale yellow with bright pink spots.
- Leaves are alternately arranged and have petioles 0.8 to 1.6 inches (2-4 cm) long.
- Leaf blades are elliptic to ovate (egg-shaped) and 1.2 to 4.7 inches (3-12 cm) long.
- Leaf margins have rounded, serrated teeth (look somewhat scalloped), with a sharp point.
- Stems are upright, often branched, glabrous (hairless), and can be tinged red.
- Height range estimates vary from up to 4.9 feet (1.5 meters), to 7.9 to 31.5 inches (20-80 cm) tall.
- Flowers produce a cylindrical to club-shaped capsule, about 1 inch long, which expels seeds when touched.
- Seeds can be expelled up to 4 to 6 feet. Seeds are black when mature.
Habitat
- Grows primarily in western Washington on moist soils at low elevations and is found in forests, lake and pond edges, riverbanks, sloughs, disturbed wetlands and sunny roadside ditches or canals.
Reproduction and Spread
- Plants reproduce by seed.
Control
- Control methods used for policeman’s helmet, Impatiens glandulifera, a Class B noxious weed in Washington, can be adapted for use on spotted jewelweed.
- Plants may have some seeds that remain in the seedbank after the first year so it is important to manage and monitor sites and provide additional control when necessary.
- Removing invasive species can open up a habitat to re-invasion if follow up management does not occur.
- By planting a variety of desirable species, a community will be present to help provide competition and shade weed seedlings and to also provide a food source for pollinators.
- When possible, carry out control methods when pollinators are not active on plants.
- Clean shoes, clothing, and equipment when leaving infested areas to prevent spreading seed to new locations.
- Can easily be hand-pulled when growing in damp soils. Make sure to remove the roots, especially in drier soils where plants may break off.
- If the plants do not have seed capsules, they can be crushed and left on site in a dry place to compost. If plants have seed capsules, make sure to bag and put them in the trash. It is important to properly identify spotted jewelweed plants before removal to avoid accidentally removing native Impatiens species.
Chemical Control
Triclopyr + 2,4-D (Crossbow, Crossroad)
- Treat in spring when plants are actively growing; summer before flowering.
- Repeat application for two years to control seedlings; avoid drift to sensitive crops; do not apply near water.
Glyphosate
- Treat in spring when plants are actively growing; summer before flowering.
- Spray complete uniform coverage, but not to the point of runoff; dust on plants may reduce effectiveness; Glyphosate is nonselective, it injures or kills any vegetation it contacts; refer to the label for use in aquatic areas.
Triclopyr Ester / Triclopyr Amine
- Treat in spring when plants are actively growing; summer before flowering.
- Spray complete uniform coverage; dust on plants may reduce effectiveness; Garlon products are registered for rights-of-way, industrial sites, and forestry sites; refer to the label for use in aquatic areas.