Plants living in ponds developed adaptations making living in an aquatic environment possible. These plants do not have to worry about drying out but enough sunshine and oxygen for photosynthesis.
Pond plants stay at or near the surface to receive adequate sunshine for photosynthesis. One species of pond plant, Duckweed, has air pockets within the tissues of the stems and leaves. Another method of staying afloat is surface tension. Large, flat objects tend to float because they cannot break the bonds of the water molecules. The Water Lily, or Nymphaea dorata, has broad flat leaves that stay on top of the water.
The roots of pond plants pull little oxygen from the mud on the bottom of their environment. Air enters the plant through stomata, microscopic air holes on the leaves, and is carried down to the roots. Carbon dioxide, combined with the heat of the sun, enables photosynthesis. Through this process, the plant makes its own food and releases oxygen back into the atmosphere through the same stomata.
Alternate Food Source
The big, floating Bladderwort, or Utricularia inflata, adapted to life in the pond by becoming carnivorous. The plant does take some of its nutrients from the water, but also catches insects in bladder-like structures and digests them using a special enzyme. The Bladderwort is found mostly in the Southeastern United States, with the exception of Western Washington in the Pacific Northwest. These plants have large, floating leaves that support showy yellow flowers that resemble snapdragons.
Ponds in colder climates may freeze over during the winter. Some floating plants go into a dormant state, called a turion. This stage of the plant does not have air pockets and it sinks to the bottom of the pond where surface ice cannot harm it. When the ice melts in spring, the plant reverts to its normal state and floats back to the surface. An example of this is the Spirodela polyrrhiza or Duckweed.