World Tree

A giant tree that gives out limitless mana. It is born of a seed known as the Mana Seed and grows by reflecting on the affection people give to it.

Tales of Phantasia
Yggdrasill, the Great Tree of Aselia, is found in the Forest of Spirits, which is the South Forest below Toltus in the present. Guarded by the Tree Spirit Martel, it is the source of mana from which magic and Spirits are born. By the start of the game, the tree has dead, leaving magic to be all but lost in the present.

At the start of the game, when Cress Albane and Chester Burklight hunt in South Forest, Cress has a vision of the tree in its healthy state and of a woman who pleads to not defile the Tree.

After traveling to the past, the Wind Spirit Sylph asks the party to see Yggdrasill. When they reach the Great Tree, Martel warns them that Yggdrasill's death is near. Normally, Yggdrasil would be able to handle the mana drain that comes with the use of magic, but some source is consuming so much mana that it is killing the Great Tree. The party resolves to stop Yggdrasill's death, as the loss of Tree would mean the loss of magic and their only hope of defeating Dhaos. Mint Adenade thinks that she could heal it with her divine power, but her spells aren't strong enough.

When Dhaos attacks Midgards, their engineers fire their magitech cannon to eliminate some of Dhaos's minions. After its firing, Martel states that mana is fading, the first hint as to what the mana depletion she warned the party about is.

After Dhaos flees the past, the party discovers a way to travel through time to chase after him. Before they leave, however, Mint reminds them that they need to save the Great Tree first. After discussing the issue with various people, Mint remembers a conversation with her mother, Meryl Adenade, about how the Unicorn is the sign of a healer and would help boost her powers. They track the Unicorn to the White Birch Forest, where, after explaining the situation and defending it from Dhaos's minions, Mint is gifted the Unicorn Horn, formed from the Unicorn's own body. With the power of the Unicorn Horn and her own strength, Mint manages to revitalize Yggdrasill, providing it with life for a while longer. It is at this point that Claus outright states that magitech is probably the cause of the severe mana drain.

When in the future, the party visits Yggdrasill once more. Martel awakens and tells them that the Great Tree is still all right because one day mana consumption returned to normal. She tells them about a handsome man with golden hair who watched over her as she slept. When Martel leaves, Dhaos arrives and it seems as if it would come to blows, but he refrains from battling in order to not harm Yggdrasill.

At the end of the game, Dhaos reveals his reasons for what he did: he wanted a Mana Seed to revive his world of Derris Karran. After his defeat, the party gathers in front of Yggdrasill to discuss this revelation. Martel reveals that Dhaos needed a Mana Seed to revive his world, but the development of magitech was killing Yggdrasill, so he fought a war to halt magitech and protect the tree. Deciding that, even if his methods were cruel, his intentions were pure, and that humans didn't need magitech, Mint erects a barrier around Yggdrasill to protect it from too much mana being drawn in order to create the Mana Seed Dhaos so desired. In the end, using Yggdrasill's gathered mana, Martel creates a Mana Seed to give to Derris Karran.

In the game's sequel, it is revealed that, much like how magitech once destroyed Aselia's Great Tree, the advent of magitech on Derris-Kharlan destroyed its Great Tree Kharlan, leading to the events of Tales of Phantasia. Dios and Meltia Bandi are the two who developed magitech and, ultimately, fired the shot which killed their Great Tree. They are reborn into Dio and Mel, and Norn, the Tree Spirit who guarded Kharlan, administers the Ordeal of Spirits in an attempt to absolve them of their past sins.

Tales of Symphonia
According to legends, the World Tree of the united world of Sylvarant and Tethe'alla was brought by the elves from Derris-Kharlan, and named it the Giant Kharlan Tree. It produces mana, which is more important than anything. Without mana, magic becomes unusable and all living things will die. It is said that mana is needed more than water.

Great Seed
The Great Seed is the seed of the World Tree. It is said in the mythology of Tales of Symphonia to be the soul of Mithos the Hero, who brought about the end of the Kharlan War in the Holy Ground of Kharlan, and gave up his soul to create the seed of the World Tree, called the Giant Kharlan Tree.

However, it is later revealed that it is not Mithos’ soul that is inside the Great Seed, but his late older sister, Martel. As she died in the Kharlan War, her soul was fused together with the seed with the help of a Cruxis Crystal in order to save it. Martel and the Great Seed are like two sides of a coin; if the Great Seed awakens, Martel’s soul will die, and if Martel is resurrected, the Great Seed will disappear, causing the end of the world.

During the game, it's discovered that the Mana links contains/protects the Great Seed, the mana from Summon Spirits of opposing elements, forms a sort of cage around the Great Seed, keeping it between the two worlds. However, when Sheena Fujibayashi formed the pact with both Undine and Volt (who has opposing elements) at the same time, neither is asleep, and the mana link is broken. The continued breaking of these links by making pacts with other Summon Spirits that causes the Giant Kharlan Tree to germinate in a twisted form, wreaking havoc on the land of Sylvarant.

But in the end, the party with the power of the Eternal Sword, recovered the seed from Mithos Yggdrasill and united the worlds of Silvarant and Tethe'alla the great seed germinated into an natural and stable form.

Backstory
In Tales of Symphonia: Dawn of the New World, it is stated by Ratatosk, the original tree's summon spirit, that the world tree of Derris-Kharlan isn't the original world tree, but one that grew from a cutting from the original world tree, which was transplanted to the united world of Sylvarant and Tethe'alla by the elves along with their arrival.

It is also stated that the united world originally existed without mana or it's influence over life, but it soon took over the role of life and magic bringer after it was brought along with the tree. Ever since then every living being in existence, including the land, had the imperious need of mana to thrive and survive.

Uncontrolled Mana Flow
Prior to the events of the game, the Chosen of Regeneration Colette Brunel, Lloyd Irving and their companions planted and successfully sprouted a new world tree and reunificated the world, that was originally divided in two by Mithos Yggdrasill's will.

With the birth of a new world tree and the reunification of the world, the land started to change violently.

It soon was found out by two Tethe'Allan scientists, Richter Abend and Aster, that the reason for this strange phenomena was that the current tree's summon spirit, Martel, could not manipulate and distribute mana as the original tree's summon spirit could and had to do in order to keep the forces of nature in balance.

After many hardships, Ratatosk agreed to help Martel restore nature's balance. However, this wasn't the only matter at hand. The Ginnungagap, the door to Niflheim was forced open and Ratatosk's existence wasn't enough to keep it secured anymore, the spirit then made a though desision.

As a vast amount of mana was needed in order to make a new seal and keep the door shut forever; and it couldn't be taken at the time without killikg the world tree's seedling or destroying the land, Ratatosk decided to modificate life laws once again, so it wouldn't ever need mana to exist, then, when the tree was old enough to bear it and life no longer needed mana to thrive most of the world's mana would be used to forge the new seal.

It was fianlly stated that even if mana stayed in the world and nourished Summon Spirits, as well as fueled magic, the world will eventually die without mana's protective properties.

Tales of the World: Radiant Mythology
The World Trees are the bases of each world. They are said to bear no fruit but provide life and mana. The World Trees give birth to Descenders whenever they are threatened, with the Descender's strength proportional to the mana the World Trees have. They may also use several Descenders, as Mormo, the Descender for Yaoon, states that he is his world's third Descender. Their roots form the earth of the world, and the towns which their roots are concentrated under are best protected from mana drain. Subsequently, when too much mana is used through the use of magitech and the like, the tree's roots retreat and are more easily destroyed. In addition, as is implied to have happened in Kanonno's world of Pasca, sometimes the World Tree is unable to restore its mana if the mana has been corrupted, leading to a steady weakening.

It is Widdershin's desire to make an unending world that fuels his quest to devour all worlds and assimilate them into his own, Gilgilum, which he has turned into seed form. To do this, he either convinces the world's Descender to combine their world with his or forcibly devours theirs. To do so, he leaves Gilgilum nodes all over the world, which drain mana, causing that World Tree to wither, retreat, and eventually be absorbed. In response to his threat, Terresia's World Tree gives birth to the Protagonist, who steadily destroys the Gilgilum nodes throughout the world. As the World Tree's health fails, however, so does the Protagonist's, who passes out after exerting great power.

When Widdershin is defeated and Gilgilum is destroyed, the World Tree finally bears fruit. Each fruit that Terresia's World Tree bears is one of the destroyed worlds, as Mormo and Kanonno discover their own. After being left alone, the Protagonist finally rests and returns to the World Tree.