(ORDO NEWS) — Sometimes the great is hidden in the small: although we usually think of trees when it comes to large plants, the modest seagrass has surpassed all sequoias and eucalyptus trees combined. A single plant occupied an area of about 200 square kilometers.
Marine flowering plants, also called “sea grasses”, are common in the warm waters of the oceans and resemble terrestrial grasses. They grow in dense clumps, like our meadows, and in many species the flowers are in spikes, like our wheat.
In addition to flowering, sea grasses can reproduce vegetatively, with the help of creeping rhizomes , from which new roots and shoots depart. In this case, genetic diversity does not increase, but one plant can cover a vast territory, becoming literally a “meadow plant”.
Because vegetative propagation makes it difficult to tell where one plant ends and another begins, the scientists had to sample the genetic material of one species of Poseidonia , Poseidonia australis , from shallow grasslands on the southwest coast of Australia.
The results were amazing: thickets of posidonia, represented by a single plant, stretched for as much as 180 kilometers, covering an area of about 200 square kilometers. Hundreds of kilometers of branched rhizomes gave rise to thousands of shoots, as a result of which the seabed turned out to be as if entangled in a living network.
Curiously, the studied sample of posidonia turned out to be polyploid , that is, when the seed was formed, the new organism inherited not half of the genetic material of the mother and father plants, but all at once.
This phenomenon is often observed in wild plants: for example, about a third of angiosperms are polyploids. Usually, polyploids are not capable of sexual reproduction and can only support themselves through vegetative reproduction.
In this case, such a plant can grow indefinitely: while some shoots and parts of the rhizome die of old age, new ones will take their place to continue the endless cycle.
According to scientists, the posidonia from the explored Shark Bay is at least 4,500 years old, which does not make it a champion in age – after all, the pine is well known, which was cut down at the age of about 5,000 years.
Nevertheless, there is no doubt that today this plant is the largest known on the planet: we have 200 square kilometers of evidence.
The only thing that can threaten the future of this unique plant is climate change: after the abnormal heat in the summer of 2010 and 2011, the posidonia thickets in Shark Bay were badly damaged, although they have already begun to recover.
Unfortunately, plants that do not reproduce sexually have little chance of adapting to changing environmental conditions due to the inability to increase their genetic diversity.
Therefore, one can only hope that the genes at the disposal of Posidonia will help it survive turbulent times and cover the sandy bottom off the coast of Australia for many more years.
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