Marine plants are not strictly a separate phylum in themselves. We will rather talk about the plant kingdom as opposed to the animal kingdom.

In fact, the plant kingdom represents all living organisms capable of producing their own organic matter through photosynthesis, thanks to the presence of chlorophyll.

The plant kingdom contains significantly fewer species, around 300,000, than the animal kingdom and when we limit ourselves to the underwater world, we find two main groups:

• on one hand, the Thallophytes with marine algae. They are made up of a thallus and lack roots, stems and leaves.
• on the other hand, the Cormophytes represented by the Phanerogams or marine flowering plants