floating pennywort
(Hydrocotyle ranunculoides L. f.)

Overview

Appearance

Hydrocotyle ranunculoides is a glabrous, stoloniferous, perennial aquatic plant. The stems float in the water or grow up onto the shore and the plants root freely from nodes about every 1.2-4 in (3-10 cm).

Foliage

The leaves are 2-6 cm in diameter and somewhat rounded with 3-7 lobes. The leaf margins are smooth to scalloped. Stalks from (5-35 cm) long are attached to the leaf edge.

Flowers

The small white, greenish, or yellow flowers are held in umbels at the ends of 0.4-2 in (1-5 cm) long flower stalks. Each flower has 5 tiny petals.

Fruit

The fruit is 0.04-0.12 in (1-3 mm) long, elliptic to round. It is flattened with faint ribs and is divided into 2 halves.

Ecological Threat

H. ranunculoides can quickly become an invasive pest when introduced to regions where it is not native. The following characteristics give it a competitive advantage: high growth rates; adaptability to changing nutrient conditions; effective vegetative propagation; plasticity in growth response; overwintering strategies that allow it to avoid low temperature stress; resistance to herbivory; resistance to chemical control; and absence of pests and diseases in the habitats where it is introduced.

Selected Images

Maps

Invasive Listing Sources

• Wisconsin Noxious Weeds
• Wisconsin's Invasive species rule – NR 40

References