Weed class: monitor list
Native to: Western Asia, India, Europe, and Africa
In the United States, it is listed by 46 states as noxious and invasive.
Why Is It a Noxious Weed?
This plant is on the monitor list. Please contact its sponsor Cathy Lucero to report locations or for more information.
How would I identify it?
This trailing, aquatic plant tends to look like a tangled cluster of leaves and stems above the water. This plant is a culinary herb known for a peppery flavor.
Clustered, 3-5 mm long white flowers appear above the water from March through October.
Older leaves are compound leaves, composed of 3 to 11 leaflets, and 4 to 12 cm long. Young leaves are simple.
Generally 10-60cm long, watercress has a fragile, fleshy stem that trails and is upright at the ends.
Where does it grow?
Watercress is generally found in cold, flowing streams and shallow fresh water.
How Does it Reproduce?
Watercress reproduces from rooting stem fragments and seeds.
For More Information
USDA APHIS page on watercress
Washington State Ecology page on watercress
Pacific Northwest Aquatic Invasive Species Profile on watercress
Invasive.org page on watercress