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.