Largest known plant in the world is 4,500 years old and stretches across 180km

Researchers have discovered what is now believed to be the largest plant in the world: an ancient specimen of an incredibly resilient seagrass that stretches across 180km and is estimated to be at least 4,500 years old.

• The single plant of Posidonia Australis was discovered in the shallow waters of the World Heritage Area of Shark Bay in Western Australia.
• Posidonia Australis stretches across 180km and is estimated to be at least 4,500 years old.
• The plant is so large because it clones itself, creating genetically identical offshoots.
• This process is a way of reproducing that is rare in the animal kingdom although it happens in certain environmental conditions and occurs more often among some plants, fungi and bacteria.

How did they found the plant?

• Researchers from The University of Western Australia (UWA) and Flinders University were taking samples of seagrass shoots from Shark Bay to generate “fingerprints” that used over 18,000 genetic markers.
• But they were stunned by the results when they did so: what they thought were different plants more than 180km apart turned out to be the exact same plant with the same genetic fingerprint. 
  
  

Unique features:

• The existing 200 square kilometres of ribbon weed meadows appear to have expanded from a single, colonising seedling.
• The plant also has twice as many chromosomes as its oceanic relatives; making it a “polyploid.”
• Whole-genome duplication through polyploidy – doubling the number of chromosomes – occurs when diploid ‘parent’ plants hybridise.
• The new seedling contains 100 per cent of the genome from each parent, rather than sharing the usual 50 per cent.
• The plant appears to be extremely resilient without successful flowering and seed production.
• It experiences a wide range of temperatures and salinities and also extremely high light conditions.