Water pennywort : Marsh pennywort. See under Marsh.

Example:


Taxonomy
Water Pennywort, plants, food, aquatic vegetation, simple flowers, aquatic plants, stalks, Leaf petioles, the leaves, mats, Plant Identification, Non-Native plants, algal, algae, Management Options, Hydrocotyle, spp, perennial plant.

Defination from the web:
... Water pennywort is a relatively small perennial plant that seldom exceeds 10 inches in height. Leaf petioles arise from creeping stems and attach to the ...