Swamps are wetlands where trees and shrubs predominate, according to the University of Minnesota's Cedar Creek Ecosystem Science Reserve. Growing with--and often in the shade of--those trees and shrubs, however, are a wide range of moisture-loving plants. With the help of these shade-tolerant swamp natives, frustrated gardeners can transform the dark, wet areas of their landscapes to bog or water gardens vibrant with the color, texture and form they've been missing.
Swamp azalea (Rhododendron viscosum) is a heath family shrub usually standing 5 feet tall and up to 12 feet wide. It grows wild in swamps and bogs from Maine to Florida and west to Texas. A loosely branching plant, it has clusters of glossy, short-stemmed green leaves that become shades of maroon or orange in autumn. Between May and August, swamp azalea has sweetly fragrant white blooms with tubular, lavender bases. Give this flood-tolerant azalea a partly shady location with wet, acidic (pH below 6.8) soil. Note that ingesting any part of the plant is toxic and potentially fatal, according to the Lady Bird Johnson Wildflower Center.
Crinum lily (Crinum americanum) is an upright, clump-forming perennial native to cypress swamps and freshwater marshes across the Southern United States. Its 2- to 4-foot leaves emerge directly from the plant's bulb. The 1-inch-thick stem, rising up to 3 feet high, has a cluster of between two and six fragrant, white ball-shaped blooms. Purple stamens and anthers contrast strikingly with their petals. Flowers appear between June and November, before the plants freeze back to water level and begin greening again. Use crinum lily, suggests the Lady Bird Johnson Wildflower Center, in water or bog gardens. It blooms in partial or deep shade. This lily requires wet, fertile, acidic locations, but isn't fussy about soil type.
Marsh marigold, often called cowslip, is a succulent buttercup family perennial. It grows wild in marshy hollows and wet woods across much of the Eastern, North Central and Pacific Northwestern United States. A stout-stemmed mounding plant, it has shiny, heart-shaped leaves. In April and May, says the Lady Bird Johnson Wildflower Center, marsh marigold's branches bear showy clusters of bright yellow blooms. They resemble buttercups far more closely than they do marigolds. The plant's new leaves are edible, but only after several rounds of boiling to remove their toxic substances. Give marsh marigold a partially shady to shady location and muddy, acidic soil high in humus.