<h2 class=" eplus-wrapper">Green planet</h2>

Beneath the sea off the west coast of Australia lies a vast green meadow dotted with purple flowers. Snub-snouted sea mammals called dugongs graze on the spring onion-like stems of seagrassThe world's only flowering plant to grow in seawater, thriving in shallow coastal areas with calm waters. They are not related to seaweed, which is actually an algae. that stretch as far as the eye can see.

This has long been known as a rare and important habitat. But now, scientists have made a discovery that gives it an even greater significance. A new study has revealed that most of this underwater lawn is in fact a single organism covering an astonishing 200 square kilometres - roughly the size of Glasgow. 

This unique phenomenon is thought to have begun 4,500 years ago with the sprouting of a single seedling. Since then the plant, known as PoseidonThe Ancient Greek god of the sea.'s weed, has been constantly cloning itself while remaining connected at the roots. It is now thought to be the largest plantBy surface area, at least. A group of aspen trees that share a root system in Utah, USA is larger in terms of its overall mass. in the world.

The plant is remarkable not only for its size and age, but also for how it has withstood enormous environmental changes. This may be due to its unusual hybridA mixture of two distinct species that combine to form one organism. nature. It contains the DNADeoxyribonucleic acid is the material in an organism that carries genetic information. of two separate species, meaning it may have adaptations that help it survive in a wide range of situations.

While the scale of this particular organism is exceptional, plants in general have a strong claim at being the most successful life form on Earth. 

In 2016 scientists conducted a "censusAn official count of the number of people in a country. In England and Wales, a census takes place every decade. " of all life on Earth, estimating the overall biomassThe total weight of a set of organisms (although the word is also used to describe a kind of energy production in which plant and animal remains are used as fuel). of various species. They concluded that plants accounted for 80% of the living matter on Earth. Bacteria made up 15%, with less than 0.5% for the entire animal kingdom.

Size isn't everything, and many scientists say that animals are Earth's dominant life form because of our intelligence. Yet an increasing number of scientists believe that our advantage in this realm is also less clear cut than it might seem.

Despite their lack of mobility, plants interact with their environment in sophisticated ways. They are thought to have between 15 and 20 senses - some similar to ours: they can sense light (sight), detect chemicals in the air (smell) and even respond to sound.

The information gathered by these senses affects the way that a plant behaves. Some notice predators or rivals and respond by emitting chemicals. Creepers can detect an object to cling to before growing towards it in a deliberate and efficient way. 

One plant, the pink-flowered Mimosa pudica, curls its leaves in response to threats. Experiments suggest that it "remembers" earlier threats for up to two months and adjusts its response accordingly, giving it a longer memory than many animals.

We rarely notice the complexity of most of these phenomena because they are either invisible or very, very slow. But as science advances, botanistsScientists who study plants. like Stefano Mancuso are arguing that these behaviours suggest mental processes at work.

Other scientists are more sceptical, arguing that intelligence cannot exist without brains. 

Regardless of their intelligence, there is no doubt that plants have the advantage in one key respect. "If we were to vanish tomorrow, the plants would be fine" Mancuso says, "but if the plants vanished... "

Yes: Our animal-centric arrogance has blinded us to the genius of plants. They have transformed the surface of the Earth more drastically than we ever will, and they'll be here long after we are gone.

No: Plants might have the numbers on their side, but nothing else in nature compares to the complexity of the brain. Animals are the true pinnacles of evolution, and humans most of all.

Or... If developments in plant science can teach us anything, it's that life on Earth is not just a competition between opposing life forms. Animals, plants and humans ourselves are all part of one great system.

Seagrass - The world's only flowering plant to grow in seawater, thriving in shallow coastal areas with calm waters. They are not related to seaweed, which is actually an algae.

Poseidon - The Ancient Greek god of the sea.

Largest plant - By surface area, at least. A group of aspen trees that share a root system in Utah, USA is larger in terms of its overall mass.

Hybrid - A mixture of two distinct species that combine to form one organism.

DNA - Deoxyribonucleic acid is the material in an organism that carries genetic information.

Census - An official count of the number of people in a country. In England and Wales, a census takes place every decade. 

Biomass - The total weight of a set of organisms (although the word is also used to describe a kind of energy production in which plant and animal remains are used as fuel).

Botanists - Scientists who study plants.