Marginal, or bog, plants grow around water perimeters. Happiest where water is calm, these plants help anchor artificial ponds to their landscapes. Functional as well as ornamental, they filter pond water and provide shade and wind protection. They grow partially submerged, directly in the soil at water's edge or in removable containers positioned on artificial underwater shelves.
Marsh birds and wildlife depend on the broadleaf cattail (Typha laltifolia) for shelter, just as the Native Americans depended on its shoots, flowers and roots for food. A sturdy perennial, broadleaf cattail produces heavy shallow-water clumps of wide, pointed green leaves. Its rigid stem can be higher than 7 feet. During spring and early summer summer, a cylindrical flower head containing both yellow male and green female flowers tops its stem. The blooms are striking additions to floral designs. Once pollinated, the female flowers produce brown seeds that remain on the stems into winter. Cattails grow in damp, rich soil or water up to 8 inches deep. They like full sun to partial shade.
Broadleaf arrowhead (Sagittaria latifolia), or duck-potato, is a 3-foot-high water plantain family perennial. Its flowering stem rises from a base of long-stalked, arrowhead-shaped foliage. From mid-summer to early fall, the plant's branches bear airy clusters of tiny white or pinkish blooms. Once a dietary staple of Native Americans, broadleaf arrowhead grows on muddy pond banks or with its lower leaves submerged in shallow water. The plant colonizes through underground runners that form its edible tubers, which are food for ducks and snapping turtles. Birds feed on the arrowhead's seeds. Broadleaf arrowhead grows in sun to partial shade.
Pickerel weed (Pontederia cordata), a 2-to-4-foot marginal perennial, thrives along calm ponds, swamps and streams. It will survive in up to 1 foot of water, according to the Lady Bird Johnson Wildflower Center. The plant holds its narrow, long, glossy green leaves high above the water. Between early summer and autumn, its erect stems have heavy, upright stalks of hyacinth-like blooms. Three to 6 inches long, the purple, blue or white flowers open in ascending order. Fish shelter beneath and deer feed on the plant. Its dried seeds are good cereal ingredients. Handling a wide range of consistently moist soils or mud, pickerel weed prefers sun or partial shade.