Virginia Tech Weed Identification Guide

Marsh Pennywort: Hydrocotyle umbellata

Weed Description: A perennial aquatic weed that spreads out horizontally forming dense mats in shallow water, mud, or in marshes.
Stems:  Stems are capable of rooting at the nodes but also may be floating.  Stems are approximately 1/4 inch in diameter.
Leaves:  Alternately arranged, round in outline, smooth, and often shiny.  Leaf margins have rounded teeth and each leaf occurs on a petiole that may reach 6 inches in length.  Leaf blades may reach 2 inches in width and are bright green in color and have veins that originate from the central point of the leaf.
Flowers:  Occur in clusters that form an umbrella-like head.  Individual flowers are very small and consist of 5 white petals but many flowers occur together in a single cluster.

Identifying Characteristics:  Aquatic perennial with round leaves that have 'scalloped' margins.  Additionally, the umbrella-like heads of small white flowers helps to distinguish this plant from most others.  Marsh pennywort is very similar to water pennywort (Hydrocotyle ranunculoides), however water pennywort has a distinctive red spot in the center of the leaves unlike marsh pennywort.