Nymphoides peltata aka Floating Heart

Nymphoides peltata, or yellow floating heart, is a water perennial. It belongs to the Menyanthaceae family, not the water lily family. Its native range covers temperate Eurasia and Algeria. It also grows across parts of the United States. The leaves float and look like those of small water lilies. It grows at pond edges and in slow-moving water.

This fast-growing plant spreads through rhizomes and underwater runners. It also grows from seed. Garden height is about 0.3–0.5 feet (0.1–0.15 m). Sources differ on spread. NC State gives 1–3 feet (0.3–0.9 m). The RHS gives a larger range of 5–8 feet (1.5–2.5 m). Plants may take five to ten years to reach full size. Their glossy, green leaves may show mottled marks. Each leaf is round, oval, or heart-shaped, with small edge teeth. Leaves measure about 0.33 feet (0.1 m) across. The plant loses its leaves in winter.

Bright yellow flowers rise above the leaves on long stalks. They open in summer, and each bloom lasts one day. The star-shaped flowers have five lobes with fringed edges. Their thin petals have a paper-like texture. Blooms measure about 0.06–0.08 feet (0.02–0.025 m) across. The floating leaves and raised flowers suit ponds and water gardens. Yet its rapid spread can make it a poor choice.

It needs full sun and standing water. NC State gives a water depth of 1–2 feet (0.3–0.6 m). It prefers sandy loam rich in organic matter. The RHS also lists clay and loam as suitable soils. It tolerates acid, neutral, and alkaline conditions. NC State lists USDA zones 5–10; the RHS rates it H6. Plants survive cold seasons at the bottom of the water. Controlling their spread can demand much work. North Carolina classes this species as a Class A noxious weed. Buying or selling it there is illegal. RHS guidance also warns against release into Irish waters.

The RHS reports few disease problems, but several pests can attack. These include water-lily beetles and water lily aphids. Brown china-mark moths and false leaf-mining midges may also cause harm. Plants For A Future lists cooked leaves and leaf stems as food. It also records cooked flower buds, stem interiors, and seeds. The leaves have a poor taste. That source reports no known hazards, rather than proven safety. It also records traditional medicinal uses for leaves and bruised plants.