There are many water plants, also called aquatic plants, that grow in natural settings such as streams, lakes and other environments. Home gardeners also enjoy growing aquatic plants in their ponds or aquariums. When choosing aquatic plants, be sure to consider a plant's sunlight needs and the environment where they'll live among other factors.
There are four types of aquatic plants. The smallest group is algae. This group of primitive plants is comprised of microscopic plants such as planktonic algae and others that are stringy and thin, such as filamentous algae. True floating plants are those that aren't attached to the bottom of a body of water, such as duckweeds and water hyacinths. Submerged plants are rooted and have most of the vegetative mass below water. Emergent plants have rather stiff stems and are rooted, generally along shorelines, above the water surface.
Aquatic plants come in various sizes. The smallest group consists of aquarium carpet plants, such as the willow moss and pygmy chair sword. The next-largest group consists of small aquatic plants such as water hedges and dwarf anubias. Medium-sized aquatic plants are the African water fern and Lobelia. Among the largest are plants such as the orchid lily and Amazon sword.
Aquatic plants are cosmopolitan, meaning they're found in water habitats worldwide. They grow along water edges, on water surfaces and on the bottoms of ponds and shallow lakes. These plants can temporarily grow in flooded regions or in drainage systems. Freshwater wetlands are areas in which half of the region's species are truly aquatic plants, which includes anywhere below sea level to high mountain habits, in which water has remained for at least a year.
When choosing aquatic plants, consider factors such as soil conditions. For example, aquatic plants such as water lilies and lotus do best when planted in heavy clay loam soils. Fertility requirements, planting techniques, water depth and containers are other considerations when gardening with aquatics. These plants should not cover more than 60 percent of a water surface.
Water temperature is important when placing plants in a pond. According to the University of Illinois, hardy aquatic plants, such as lotus, can be placed in ponds with temperatures as cold as 50 degrees Fahrenheit, but some floaters and tropical water lilies are intolerant of cold temperatures and shouldn't be placed in water temperatures lower than 70 degrees Fahrenheit. Placing these plants prematurely can cause damage, dormancy and limit a plant's potential for growth.