Yellow Water-Lily (Nuphar variegata)
Yellow Water-Lily & White Water-Lily floating leaves and Yellow Water-Lily Flower
Yellow water-lily is easily identified by its emergent yellow flower and giant floating erect leaves which can be as long as 12 to 15 inches. The leaves are large with lobed ends where the stem is attached. The stem of the leaf is triangular in shape. The yellow flower petals appear cupped around the inner flower parts and do not open completely like white water-lilies.
Identification Tips: Yellow water-lily is often confused with floating heart and the white water-lily. Floating-heart, however, is much smaller in leaf length, and white-lilies have a much more rounded leaf with a sharp v-notch (see photo above). (Source: Aquatic Plants and Algae of New Hampshire's Lakes and Ponds)