Marsilea quadrifolia, commonly known as European Waterclover or Four-Leaf Clover, is a deciduous, perennial herb native to still or slow-moving freshwater habitats such as ponds, ditches, and marshes across Europe and Asia, and has been introduced to parts of the United States. It typically forms dense mats with creeping rhizomes. The plant is notable for its clover-like leaves that emerge on long petioles from the water surface. Each leaf is divided into four leaflets, giving it a resemblance to the lucky four-leaf clover. The inconspicuous sporocarps, which contain the spores, are produced underwater and are rarely seen.

European Waterclover is valued for its ornamental appearance, especially in water gardens and ponds. It can provide a natural filtration system by absorbing excess nutrients from the water, thus helping to maintain water clarity. This plant prefers full sun to part shade and thrives in shallow water or saturated soil. It is relatively low maintenance but may require control to prevent it from becoming invasive. In regions where it is not native, it can outcompete local flora and alter aquatic ecosystems.CC BY-SA 4.0