Marginal Plants
At the edge, or margin, of the pond, where the soil is moist or the water shallow, grow the "marginals." These plants have their roots in soil and most of their foliage is out of the water. Some grow in soil that is only moist and wet; others grow in submerged soil--from a few inches to about 2 feet. Many marginals will also adapt to the perennial garden, as long as the soil is kept fairly moist. This adaptability makes them ideal as transitional plants that link the pond with other gardens.
Marginals can be taller than 6 feet or less than 2 inches in height, Some are clump-forming, such as hosta, and stay where they're put. Others are rambling types that traverse the pond edge. Their chief function is decorative, adding color, texture, and form to the design. They're also an important transitional element in the landscape.