Common Names: Water pennywort

Description: Native to North America but displays many invasive characteristics.

Habit: Extremely fast growing floating aquatic plant, can grow up to 20 cm per day and 15 m from the bank in a single season and can double its biomass in 3-7 days.

Leaves: 2-6 cm in diameter, rounded or wider than long, with 3-7 lobes. Lobe divisions extend to about mid-leaf. Leaf edges are smooth to slightly scalloped. Slender stalks 5-35 cm long are attached to the leaf edge.

Stems: Pale green to brownish white, round in a cross section and glabrous; they are rather thick and fleshy and can float on water.

Flowers: Very small creamy yellow flowers (usually 9) approximately 3 mm in diameter on a short umbel below the leaf canopy.

Fruit and seeds: The fruit is 1-3 mm long, elliptic to round, and flattened with faint ribs. It is divided into 2 halves, each with a tiny stalk.

Habitat: Native to North and South America. Found in freshwater lakes, reservoirs, ponds, marshes and slow-flowing streams and rivers.

Reproduction: Vegetatively from fibrous roots.

Similar species: May be confused with other Hydrocotyle or Ranunculus species.

Monitoring and rapid response: Hand pull or remove by machine for small infestations. Physical removal should be completed before flowering and seed set. Registered aquatic herbicides can provide some control in small scale applications.

Credits: The information provided in this factsheet was gathered from the Wisconsin Department of Natural Resources.

Individual species images that appear with a number in a black box are courtesy of the Bugwood.org network (http://www.invasive.org).Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (http://images.google.com).

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