Cardamine hirsuta

Cardamine hirsuta

Hairy bittercress
Binomial:	Cardamine hirsuta
Type:	Winter annual
Conditions:	Adaptable
Seed Dispersal:	Explosive capsules, small seeds easily moved on clothing
Germination Time:	Mid-autumn
Vegetative Spread:	None

Hairy bittercress, Cardamine hirsuta, is a winter annual plant native to Europe and Asia, but also present in North America as an invasive weed. The plant is a member of the mustard family (Brassicaceae), and is edible as a bitter herb. Other common or country names include bittercress, land-cress and lamb's cress.

Description

Hairy bittercress germinates in autumn, and is present through the winter as a basal rosette of pinnately compound leaves. It flowers sporadically in autumn, and then from late winter through spring. The small white flowers are borne in a corymb on wiry green stems, soon followed by the seeds and often continuing to flower as the first seeds ripen. The seed are borne in siliquae which, as with many Brassica species, will burst explosively, often when touched, sending the seeds flying far from the parent plant. Seeds germinate in the Autumn, and the plants are green throughout the winter months.

C. hirsuta growing in a pathway

Ecology

Hairy bittercress can be very invasive and often arises when seeds are introduced unintentionally in the soil of plants that have been brought home from a nursery or garden center. This plant grows best in consistently damp, recently disturbed soil. These are conditions that are prevalent in nursery-grown plants, and hairy bittercress may "hitch a ride" in the containers.

Uses

Can be eaten as a bitter herb.

During the winter months, this plant can be left in place as a cover crop on bare soil, though it should generally be flamed or tilled in before it sets seed unless one intends to use it as a winter cover the next year.

Control

• Mowing: Not effective, as the plant grows quite low, and can flower and set seed within a few days
• Cultivation: Effective on young plants that have not yet flowered
• Mulching (for prevention): Mulching in late summer will prevent germination
• Pulling: Pulled plants should be placed directly into a container, as the seeds will continue to ripen even after the plant is pulled up.
• Flame: Flameweeding is effective.
• Disposal: Hot composting only if seeds are present.