Narrow-leaved bitter-cress

Cardamine impatiens

Invader Images

    • Narrow-leaved bitter-cress foliage
    • Basal rosette
    • Narrow-leaved bitter-cress flower
    • Narrow-leaved bitter-cress stem
    • Infructescence

Identification

Appearance

Cardamine impatiens is an herbaceous plant which can be an annual or biennial. It can grow to be 2 ft. (0.6 m) in height. The stem is erect and glabrous. It is somewhat shade tolerant, so it does well in forest edges or dappled sunlight. It also does well in areas that have moist soil.

Foliage

The leaves (6-20) are thin and membranous. The basal rosette of leaves are pinnately divided. Each leaf has 3-11 leaflets with rounded lobes. The leaves along the stem are also pinnately divided, with sharply toothed or lacerate leaflets. These leaves are sagittate auriculate (a pair of fleshy blunt projections turned downward) at their base, which is an important diagnostic characteristic.

Flowers

The plant blooms from May to August and its white flowers are small, being up to 0.1 in. (2.5 mm) long.

Fruit

The slender siliques (a type of fruit) ripen from May to September. They are 0.6-0.8 in. (1.5-2 cm) long and there are 10-24 seeds in each of them which shoot out from the dry fruits.

Biology

This is considered a watch list species.

origin

It is not known how narrow-leaved bitter-cress came to the United States from Europe. However, the first record of the plant in New England was from Peterboro, New Hampshire in 1916. The plant then appeared in Connecticut, followed by a subsequent spread across Connecticut, and later reports from Massachusetts (1991), Vermont (1992), and Acadia National Park in Maine (1994).

habitat

Early successional forest, forest edges, floodplain forest, herbaceous wetlands, rivers and streams, roadside, vacant lots, yards, and gardens.

life Cycle

Narrow-leaved bitter-cress is an annual or biennial plant that can grow up to two feet in height. The plant’s small white flowers bloom from May to September.This plant is able to spread easily due to its seed-shooting ability. Each flower contains ten to 24 seeds. Seeds are also spread by water and can stick to clothing and animals.

ecological threat

Narrow-leaved bittercress produces many seeds per plant. It can form dense stands invading woodland habitats and outcompete native species.

Management Options

mechanical control

Hand-pulling can be effective with small infestations. Monitor the site and remove plants during the spring, summer and fall to prevent seed production. Plants with flowers and seed heads should be bagged and disposed of in a landfill. Hand-pulling is not recommended for large infestations as it might cause disturbances that will result in more seed germination.

chemical control

There is little information available for chemical control of this plant. However, treatment protocols for biennials like garlic mustard may be effective. A systemic herbicide like glyphosate or triclopyr may be applied to the leaves at any time of the year, as long as the temperature is above 50 degrees Fahrenheit and it is not expected to rain for at least eight hours.

 

**Be careful not to damage or kill nearby native plants when conducting management work. And when using herbicides, always follow the instructions on the label.**

Citations

photo credit

Narrow-leaved Bitter-cress, 5449287, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Basal rosette, 5270063, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Stem morphology, 5270064, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Infructescence, 5270068, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Flower, 5449232, Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

information credit

Center for Invasive Species and Forest Health, Cardamine impatiens

GoBotonoy, Cardamine impatiens

Invasive Plant Atlas of New England

Minnesota Department of Agriculture

Pennsylvania Department of Conservation and Natural Resources