3 main types of aquatic plant for the pond:
These each live in a different area of the pond and have a different function to each other.
If a plant is totally submerged below the water it is known as an oxygenating plant as all its surfaces are under the water and capable of releasing oxygen to keep the water healthy.
Some floating plants are rooted in the depth of the pond but with floating leaves - like waterlilies or Water Hawthorn and others float freely in the water like Frogbit but both cover the water surface with their leaves.
Covering the surface water is important so that the water temperature remains cool for fish and wildlife. Shade from the leaves also helps reduce algae growth. Flowers are an added bonus.
These are rooted into soil below the water level (either in a basket or in the edge of a clay pond) but most of their leaf, flower and stem are above water. These emergent pond plants grow from the shelf area of a man-made pond or round the rim of a natural clay pond. These plants use nutrients to put on growth and flower at different times of the season that create the visual of the pond you see.
Some emergent pond plants are called rafting plants because, although they grow like emergents from below the water surface, they do not emerge and grow tall and upright but they have horizontal growth that rafts across the water surface.
You need a combination of all 3 of these plant types to make a successful and balanced pond area.