Scientists were ‘blown away’ when they stumbled upon the largest known plant on earth during a recent study of seagrass meadows.
110 miles in length, the study’s authors could barely believe what they were seeing when carrying out research in Australia’s Shark Bay World Heritage Area.
The plant in question is Posidonia australis, a type of ribbon weed seagrass that thrives in shallow, sun-drenched waters.
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Scientists were interested in learning how underwater seagrass meadows grow, so tested the plants’ DNA, which is when they discovered they were dealing with just one organism.
Writing in Science Alert, Elizabeth Sinclair, one of the scientists involved in the study, explained her team collected shoot samples from ten seagrass meadows and the results showed that 77 square miles of ribbon weed meadows expanded from a single seedling.
While it’s ‘challenging’ to know the plant’s exact age, Sinclair said based on its size and growth rate, the seagrass is likely around 4,500 years old.
As for how it came to be, Sinclair pointed to the fact that the seagrass plant in question is unique because it has twice as many chromosomes as its relatives, making it a polyploid.
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Polyploids carry the entire genome of their parents and can grow indefinitely if not disturbed, as this seagrass has done.
Sinclair also emphasised the importance of the discovery, which speaks to the plant’s ability to grow in variable conditions.
She said: “It appears to be really resilient, experiencing a wide range of temperatures and salinities plus extreme high light conditions, which together would typically be highly stressful for most plants.”
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The sprawling plant provides habitat for all sorts of marine species, including turtles and dolphins.
New South Wales’ Department of Primary Industries describes Posidonia australis as a ‘large, bright green, strap-like leaves that can grow to over 80 cm long’.
Its description continues: “They are usually 6-14 mm wide with rounded ends. As much as 90 percent of the mass of the plant may be in the roots. They can be found in large meadows at shallow depths in estuaries, coastal lakes and sheltered coastal waters.
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“As one of the slower growing species of seagrass, Posidonia australis can be particularly slow to recover from damage.”
The government website notes that the plant is most commonly found in the southern half of Australia and is particularly important because of its ability to remove carbon dioxide gas from the water.
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Aisha Nozari