Marsh plants, sometimes called bog plants, are those species which can grow in permanently moist soil, but which cannot tolerate flooded soil or having their crown or foliage underwater all year round. Many plants sold as pond plants are in fact marsh plants. Marsh plants can be planted around the edges of the pond, where the soil is wet. All marsh plants will also grow perfectly happily in a standard flower bed as a 'normal' garden plant. Although they will obviously not tolerate drought, they do not actually require wet soil in order to grow well.
There is an extremely wide range of marsh plants (far wider than true pond plants). Here at Water Garden Plants we focus on rare native marsh plants which are difficult to find elsewhere.