Hydrocotyl, or Hydrocotyle ranunculoides, is a creeping aquatic or semi-aquatic plant recognized by its rounded, scalloped leaves held on long petioles that float or hover just above the water. Sometimes called floating pennywort, Hydrocotyle ranunculoides forms dense mats across ponds, wetlands, and slow streams. Its stems trail horizontally, rooting at nodes and expanding quickly across the water’s surface. Native to the Americas, it has spread to other continents, where its rapid growth can overwhelm native species.

One of its defining traits is versatility: Hydrocotyle ranunculoides thrives in both shallow water and damp soil, allowing it to move between habitats with ease. The floating mats reduce light penetration, influence temperature, and provide cover for aquatic organisms. Its soft, rounded foliage gives it a gentle appearance, yet Hydrocotyle ranunculoides is remarkably assertive in suitable environments.