Building a pond in your backyard creates a soothing retreat for yourself and for wildlife. Whether the pond is large or small or lined with plastic or rocks, plants are beneficial in many ways, including discouraging green-water algae from forming by shading the water from the sun.
Rooted Floating Leaf Plants
The roots of these plants need soil, whether in a container of soil or at the bottom of an earthen pond, according to "Water Gardening Basics" by Helen Nash and Marilyn M. Cook. These plants have long stems that grow upwards and float along surface of the water. This type of plants includes water lilies--both hardy, which can survive frost, and tropical--and floating hearts, a plant with floating leaves and flowers which bloom during the summer months.
Floating Aquatic Plants
The roots of these plants take their nutrients directly from the water, according to "The Complete Guide to Water Plants," by Helmut Muhlberg. Examples of this plant include the water fern, which has round, floating leaves; the azolla, a small fern with scale-shaped leaves; and duckweed, a perennial that grows quickly and is considered an invasive plant.
Marginal plants grow with their roots anchored in the soil of an earthen pond and their stems, leaves and flowers growing above the water, according to "Rock and Water Gardens," by Ogden Tanner. Like water lilies, marginal plants are divided into hardy and tropical varieties. Examples of hardy marginal plants include arrowhead, whose leaves are shaped like arrows; pickerel weed, which has finger-shaped leaves; the iris, which is available in different varieties ranging from sun to shade-loving types; and cattails. Tropical marginal plants include elephant ear, characterized by its large leaf that resembles an elephant's ear; umbrella palm, which averages 1 to 3 feet in height with yellow to orange flowers; and canna, a tall plant that grows to over three feet and features pink to red flowers.
Submerged plants grow entirely underwater and receive their nutrients from the surrounding water. Examples include pondweed, which has oblong leaves and blooms in the summer; coontail, a perennial that is classified as an herb and grows quickly; and cabomba or fanwort, which has fan-shaped leaves.