Water gardens accommodate many different types of plants. It can be a challenge to know if that lovely little white flower floating on the surface of the pool is a bog plant, floating plant or miniature water lily. Algae is a common water plant but is recognizable to most gardeners because the water turns green. Identify other water plants by how and where they grow.
Determine how far underwater the roots of the plant are. If the plant is growing where the leaves are above the water and the roots are no more than 4 to 6 inches under the water, the plant is a bog plant. Bog plants like their roots constantly wet but won't grow well if the majority of the leaves aren't above the water. Bog plants include radicans with leaves shaped like hearts, mellon sword with sword-shaped leaves and dwarf papyrus which has long stems up to 3 feet long with clusters of leaves at the top.
Pick up the plant if it is floating in the water. If you can completely remove the plant and it's not rooted in soil, then it's a floating water plant. The plant goes where the water current goes, since it's not attached to the bottom of the pond. Floating water plants come in a variety of leave shapes, sizes and formations. Water hyacinth has bulbs filled with air that keep it floating. It has purple flowers held above the leaves. The roots provide a safe haven for fish fry. Salvina has rectangular-shaped leaves with round corners that are about 1/2 inch long. Duck weed has very small leaves no bigger than a pencil eraser.
Look to see if the plant is completely underwater. If so, then it's an oxygenating plant. These plants remove ammonia from the water and add oxygen. They're important in controlling algae and keeping the water clear. Oxygenating plants are rooted in the bottom of the pond. Money wort has small, rounded leaves that grow in opposite pairs. Red hygrophila is a muted red color with broad leaves. Sagittaria grows in rosettes and throws out runners to form new plants.
Gently tug on the rounded leaf of a floating plant. If it doesn't budge it is rooted in the pond. Water lily have round lily pads and cup-shaped flowers with many petals. Colors include pink, yellow, red and white for hardy water lilies. Tropical water lilies bloom in blue and purple, as well as the colors of the hardy lilies. Snowflakes have leaves that look like tiny lily pads. However, their flowers have five to seven narrow petals and are white, or, in the case of the yellow-flowered snowflake, yellow.
Look to see what size and how the leaves are formed. If the leaves are from 12 to 24 inches across and concave and the flowers are held on stems above the water, you're looking at a hardy lotus.