| MadSci Network: Botany |
The only actual plants (Kingdom Plantae) that live submerged in the oceans are the seagrasses, which form large underwater meadows in shallow water off south Florida, Western Australia and in the Mediterranean Sea. Seagrasses have true roots which can function in mineral nutrient absorption but do not really need to absorb water. Seagrasses are considered to represent once-terrestrial plants that returned to the sea. Large marine algae, such as kelps, are not true plants. They are in Kingdom Protista. Kelp have holdfasts which only serve to anchor the plant. Holdfasts are not structurally similar to true roots. References What are seagrasses? Seagrasses South Florida Seagrass Giant Kelp Holdfast
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