Water gardens are a popular way to bring an interesting element to a garden or outdoor living space. Common plants for water gardens are planted in submerged pots, or directly at the bottom of a water garden, where they are anchored in soil. Interesting types of plants that will grow in water without being anchored are known as floating plants. Floating plants filter and clean impurities from the water, and they help reduce unwanted algae. They provide places of respite for fish and frogs.
Anacharis is a feathery looking plant, with stems that are covered with needle-like leaves. It sometimes anchors in the bottom of a pond. More commonly, bits of the plant that break off will float and grow into a mat, completely unattached. Anacharis gets the nutrients it needs through its leaves, so it is not dependent on roots except as anchoring mechanisms.
Water-hyacinths are excellent plants to grow in a pond or water garden. The leaves grow in rosettes, with pretty flowers forming occasionally. The long roots dangle in the water beneath the floating plants. Water-hyacinths are so good at purification that they are used in water treatment facilities in the Southern U.S.
Frogbit has rosettes of 1-inch leaves that resemble small versions of lily pads. The leaves are puffy underneath, which makes them buoyant. You may see small white flowers in a mass of floating frogbit. The plants propagate by producing new rosettes of leaves on stems, which spread over the surface of the water.
Water lettuce plants look like small, floating cabbage plants. The leaves are ribbed, about 4 inches long on a mature plant, and they grow in a rosette. A mature water lettuce plant produces stems from the sides that develop baby plants at the tips. The baby plants can be separated from the parent when the leaves reach 1 to 2 inches. Mature plants may turn yellow; remove them from the colony to keep it green.
If you have fish in your water garden, they will enjoy a colony of butterfly fern floating plants. Butterfly ferns have small leaves, about 1/2 inch, that form a floating mass. Fish like to nibble this plant, and they also like to hide in the shade it provides.