- Bald cypress grow in floodwaters.VisionsofAmerica/Joe Sohm/Digital Vision/Getty Images
Most plants need a supply of oxygen to their roots to maintain proper growth. For most plants, it's difficult for a plant to get an ample supply of oxygen to its roots when growing directly in the water or in water-logged soils. Some plants, however, are suited to overly wet habitats, and thus thrive with little competition where other terrestrial plants couldn't survive. - Bald cypress knees provide support and oxygenate the roots.cypress knees image by Earl Robbins from Fotolia.com
The American Southeast is the native range of the bald cypress tree (Taxodium distichum). It grows there along stream banks and in flood plains and swamps, often in up to 3 feet of water. Many of the native wetlands in the gulf states are cypress swamps dominated by bald cypress in flowing water, and the closely related subspecies pond cypress (Taxodium distichum var. nutans) in still water. Both types are deciduous conifer trees reaching a maximum of 150 feet tall, with the pond cypress slightly smaller than the bald cypress. They produce thick buttressed trunks that allow them to withstand hurricane-force winds even though they're shallowly rooted in muddy soil. They're further aided by woody knees that punch up from the soil around the roots. These structures are thought to aid in oxygenation and are produced only by trees growing in inundated soils. Bald cypress trees can also grow on drier sites and in cold climates such as Minnesota and southern Canada. They do best in moist soil that's slightly acidic, and they need full sun. - Water lettuce reproduces by producing numerous side shoots.laitue d'eau image by Unclesam from Fotolia.com
Water lettuce (Pistia stratiotes) is a tropical floating plant that resembles a small head of lettuce about 6 to 10 inches in diameter with pale-green fuzzy leaves that are thick. Beneath the rosette of leaves are long, fibrous roots that can hang down several feet or root in the substrate. The origin of water lettuce is unknown, but humans have spread it around the tropical world, where it's become an invasive weed in many areas. This plant has the potential to quickly clog streams and lakes and prevent boat traffic. It also blocks light and robs native species of nutrients. Water lettuce is a favorite plant for freshwater ponds in gardens. It's treated as a summer annual and suffers damage and dies off when temperatures reach below 59 degrees. It requires little to no care; just float a rosette in full sun in a pond, and the plant will spread until cool temperatures kill it in the fall. - Papyrus is native to the marshes along the Nile River.Papyrus and morning sky reflecion, HaHula, Israel image by Oren Sarid from Fotolia.com
The ancient Egyptians were known for taking the stalks of the papyrus (Cyperus papyrus), pressing them together and creating some of the first paper used by humans. Papyrus is native to the marshes along the Nile River, where it grows with its roots below the water in the soil, and its reed-like, 10- to 15-foot-tall stalks above the surface. Papyrus can be used as an annual in climates that freeze, or as a greenhouse pond plant. It prefers to be rooted in shallow fresh water but can also tolerate moist soil. For pond use, plant it in commercial pond substrate in containers and place them around the pond margins in full sun. It can be removed at the end of the season or wintered in the greenhouse.
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