3 main types of aquatic plant for the pond:
Each type of aquatic plant lives in a different area of the pond and has a different function.
Totally submerged aquatic plants are known as oxygenating plants. All its surfaces are under the water and capable of releasing oxygen to keep the water healthy.
Some floating aquatic plants root in the depths of the pond but with floating leaves - waterlilies or Water Hawthorn. Others float freely in the water like Frogbit - both cover the water surface with their leaves.
Covering the water is important so that the temperature remains cool for fish and wildlife. Shade from the leaves also helps reduce algae growth. Flowers are an added bonus.
These pond plants root into soil below the water level. Most of their leaf, flower and stem are above water. These plants use nutrients to put on growth and flower at different times of the season. Emergent pond plants grow from the shelf area of a man-made pond or round the rim of a natural clay pond.
Some marginal shelf pond plants are called rafting plants. They grow from below the water surface but they have horizontal growth that rafts across the water surface not upright growth.
You need a combination of all 3 of these aquatic plant types to make a successful and balanced pond area.