Spotted Jewelweed
Impatiens capensis
Washington State Classification
Class C — Widespread, County-Selected Control
This is a new noxious weed for 2018.
Quick Reference
Identification
Growth Habit
Spotted jewelweed is an 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.
Leaves
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.
Flowers
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.
Fruit & Seeds
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.
Impact
This is a new noxious weed for 2018. Spotted jewelweed has spread rapidly since it was first documented in Washington. 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.
Ecology & Spread
Habitat
Spotted jewelweed 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. Click here to view a county level distribution map of spotted jewelweed.
Spread Mechanisms
Reproduction
Plants reproduce by seed.
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