Nymphoides peltata (syn. Villarsia nymphoides, Limnanthemum nymphoides) – Water Fringe very much resembles a miniature waterlily with its 2 to 4″ wide heart-shaped green leaves (that float on the surface) and funnel shaped bright yellow flowers (with fringed edges) that rise above the water from July to September. Water depth 8-24″ (can go in deeper). Indefinite spread. Zone 6.
Menyanthes trifoliata – Bog Bean is a genus of one with trifoliate mid-green leaves (leaflets about 4″ long) that sit above the water’s surface. It bears fringed fragrant white flowers (emerging from pink blushed buds) held in clusters of 10-20 on stalks from May to June. Bog Bean often forms large colonies in natural ponds. Grows 8-12″ high. Indefinite spread. 2-8″ water depth. Zone 3.
Orontium aquaticum – Golden Club is another single species genus that features bluish-green foliage that may be submerged, floating or above surface. They much resemble skunk cabbage (but are smaller) and water beads off the leaves. Interesting yellow spadices are borne on white pencil-like stalks in spring. Grows 12-18″ high by 24-30″ wide. 4-6″ depth. Zone 6.
Lysichiton camtschatcensis – This relative of the Skunk Cabbage is an RHS Award of Garden Merit winner and a native of northeast Asia. It can be hard to find and features pure white spathes (often green tinged) wrapped around a green spadix with a musky aroma. This herbaceous perennial blooms as the leaves emerge. Tolerates part shade. Grows 24-30″ high by 30-36″. 0-1″ depth. Zone 5.
Lysimachia punctata – Yellow Loosestrife is a vigorous herbaceous perennial with tall spires of star-shaped blooms appearing from June to August. It is a bit aggressive and should be containerized to restrict growth unless broader coverage is desired. Most gardeners hard prune after flowering. Part to full sun. Grows 2-3′ high and wide. 0-1″ water depth. Zone 3.