Posidonia australis: World's Largest Plant

Scientists have discovered the world's largest plant off the Australia coast—a seagrass meadow that has grown by repeatedly cloning itself.

The single plant of Posidonia australis was discovered in the shallow waters of the World Heritage Area of Shark Bay in Western Australia.
Genetic analysis has revealed that the underwater fields of waving green seagrass are a single organism covering 70 square miles (180 square kilometers) through making copies of itself over 4,500 years.
Scientists confirmed that the meadow was a single organism by sampling and comparing the DNA of seagrass shoots across the bed.
The scientists call the meadow of Poseidon's ribbon weed "the most widespread known clone on Earth," covering an area larger than Washington.
Though the seagrass meadow is immense, it's vulnerable. A decade ago, the seagrass covered an additional seven square miles, but cyclones and rising ocean temperatures linked to climate change have recently killed almost a tenth of the ancient seagrass bed.