Scientists Discovered World’s Largest Plant at Shark Bay

Shark Bay in Western Australia is a World Heritage Area known for its temperate seagrass meadows. Scientists from the University of Western Australia and Flinders University recently discovered the world's largest plant at Shark Bay.

Posidonia australis, an ancient and incredibly resilient seagrass that stretches 180 kilometres and is estimated to be at least 4,500 years old, was discovered.

"The project began when scientists wanted to understand how genetically diverse the seagrass meadows in Shark Bay were and which plants should be collected for the seagrass restoration," said Dr. Elizabeth Sinclair of UWA's School of Biological Sciences and the UWA Oceans Institute.

"We are frequently asked how many different plants grow in seagrass meadows, and this time we used genetic tools to answer that question."

"The team sampled seagrass shoots from across Shark Bay's variable environments and generated a 'fingerprint' using 18,000 genetic markers," said UWA student researcher Jane Edgeloe, a lead author of the study.

"The answer astounded us – there was only one! In Shark Bay, a single plant has spread over 180 kilometres, making it the largest known plant on the planet."

"The current 200km2 of ribbon weed meadows grew from a single, colonizing seedling."

"Aside from its enormous size, what distinguishes this seagrass plant from other large seagrass clones is that it has twice as many chromosomes as its oceanic relatives, indicating that it is a polyploid."

"When diploid 'parent' plants hybridize, whole-genome duplication through polyploidy – doubling the number of chromosomes – occurs." The new seedling has 100 percent of each parent's genome, rather than the usual 50 percent."

"Polyploid plants frequently live in extreme environmental conditions, are often sterile, but can continue to grow if left alone, and this giant seagrass has done just that."

"Even without successful flowering and seed production, it appears to be resilient, surviving a wide range of temperatures and salinities, as well as extreme high light conditions that would be highly stressful for most plants."