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.
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 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. To put that into context, this single plant has grown across a dance larger than that between Mumbai and Pune, which are about 150km apart.
The study has been published in an article titled, “Extensive polyploid clonality was a successful strategy for seagrass to expand into a newly submerged environment,” published in Proceedings of the Royal Society B.

Evolutionary biolog Elizabeth Sinclair from UWA, who is a senior author of the study said in a press statement that the research project began when researchers wanted to understand how genetically diverse the seagrass meadows in Shark Bay were. They also wanted to know which plants should be collected for seagrass restoration.Best of Express PremiumPremiumPremiumPremiumPremium
“The answer blew us away – there was just one! That’s it, just one plant has expanded over 180km in Shark Bay, making it the largest known plant on earth. The exing 200 square kilometres of ribbon weed meadows appear to have expanded from a single, colonising seedling,” said UWA student researcher and lead author of the study, Jane Edgeloe, in a press statement.
Its enormous size is not the only thing that sets it apart: 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,” said Sinclair, in a press statement.
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. Usually, this would be highly stressful for most plants, but the giant plant seems to thrive in these conditions.