There are many types of pondweeds found in freshwater lakes and ponds around the world. Most pondweeds have small flowers that grow on top of the water, while most of the rest of the plant is submerged in shallow water, sometimes the plant floats on the surface.
All pondweeds have their roots firmly underwater and are green, but their leaves are of different shapes, and sizes. These plants’ greatest adaptation is to living in water, which is their main life giver.
These plants have many cells on their leaves (surface cells) can absorb water, nutrients and even dissolve gasses. This means that the plants internal system that would otherwise be transporting these nutrients either does not function at all, or functions very slowly.
These plants also do not have breathing holes in their leaves (pores) nor do they have the usual amount of protective tissue normal plants have that prevent a lot of water being lost.
The root system of pondweeds does not function, as do most plant root systems by providing nutrition. These roots only make sure the plant is anchored safely to the ground. The root hairs are sometimes not there at all, like in the case of the bladderwort.
As would be expected, the leaves of pondweeds play the most important role in the life of the plant and each species of pondweed as a specific shape to its leaves.
Underwater plants have leaves, which are divided very finely. This creates a bigger area for photosynthesis, and reduces water resistance (that can be damaging to the plant).
Some plants have different shaped leaves growing on them (Heterophylly), which makes it very difficult to identify these plants. Botanists have found that in most plants the shapes of the leaves that are on the surface of the water are different to the leaves that are underwater, in the same plant.
They have found that in the Heterophylly plants, the leaves on top of the water are less divided, similar to the leaves on plants on land.
Pondweeds and other aquatic plants have air-filled areas inside their leaves and stems. These pockets are oxygen sources for beetle and fly larvae that pierce the stems or leaves with a little gadget on the stomach.