This world is all water, and I want the trees to be the only thing that represents land. The trees are horizontally positioned, and start from a large self sufficient floating seed pod, much like a coconut would. They would lengthen faster than they would widen, during the growth process.

Naturally the size of these are twenty thousands of times bigger than the widths of the giants of earth. The roots would glean nutrients from the water, and have some kind of mechanism for trapping the fish for food, thus categorizing the tree as carnivorous. The structure is questionable as far as shape and anatomy of its trunk, limbs, and bark. All those things would have to be shaped so that the the tree is habitable for humans.

What could I improve to make this more believable, or is it believable at all?

  • $\begingroup$ Welcome to Worldbuilding! I edited your question a bit to make it more clearly divided into a background section and a question section. $\endgroup$
    – kingledion
    Commented Nov 15, 2016 at 18:50
  • $\begingroup$ Welcome to the site Conrad. If you have questions on how things work check out the help center and once you gain some more rep feel free to visit us in Worldbuilding Chat $\endgroup$
    – James
    Commented Nov 15, 2016 at 19:25
  • $\begingroup$ Could you allow it to be 'plants' instead of 'trees'? I am imagining a massive, dense, strong version of water lettuce or the jumbo hyacinth. But these are not trees. $\endgroup$
    – Mikey
    Commented Nov 15, 2016 at 21:02
  • $\begingroup$ Related, may or may not be duplicate: worldbuilding.stackexchange.com/q/54293/10851 $\endgroup$
    – cobaltduck
    Commented Nov 15, 2016 at 21:16
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    $\begingroup$ I'm pretty sure that some cypress tree forests come close, and there is fossil evidence of a tree fern which was potentially free-floating. $\endgroup$
    – Hot Licks
    Commented Nov 16, 2016 at 3:14

5 Answers 5


The concept you have in mind is plenty believable for fiction but there are a few changes I think would be necessary.

These aren't going to be trees. Tree is a specific name for a specific type of plant.

Trees require soil and can't handle salt water (in most situations). They are also generally hard and inflexible which would be detrimental if they exist in a medium that is constantly in motion, meaning the ocean.

So in short the type of plant you describe could likely exist but it would definitely not be a tree. It would likely be some sort of super seaweed. You would also probably need to consider allowing your super seaweed to take root in shallow waters allowing for more nutrients and larger growth. The size you are looking for will be tough to get to if they are completely free floating all the time.

It may not be relevant to your story but in your head you should also probably consider that they had to have evolved the ability to trap and consume fish if you want to go that route meaning that being able to take root or something similar would have been needed earlier in the evolutionary history of the organism.

Also...humans wouldn't evolve as humans on this world so keep that in mind...either they are transplants or humanoid but not quite human.

  • $\begingroup$ "Tree is a specific name for a specific type of plant." Actually it's a specific name for two completely unrelated types of plant. Unrelated except for the fact that they both grow vertically around a central trunk or trunks. $\endgroup$ Commented Nov 15, 2016 at 22:05
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    $\begingroup$ @RBarryYoung Context on those two "completely unrelated" plants? I'm interested $\endgroup$
    – Zxyrra
    Commented Nov 16, 2016 at 0:07
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    $\begingroup$ @Zyyrra Trees evolved at least twice (some extinct Lycopsids, for example are considered trees), of the living groups the first was the Gynosperms about 319 mya which is what Conifers ("evergreens", etc.) are. Sometime between 160 and 190 mya, Angiosperms (all flowering plants) developed from some non-tree gynosperms (possibly seed ferns). These first angiosperms were not trees, but later the larger woody bushes evolved into trees. Even today, many angiosperm can be either a tree or a bush depending on how you prune it. $\endgroup$ Commented Nov 16, 2016 at 13:49
  • $\begingroup$ Thanks again for your support and advice. Zyyrra, you are correct, and this was my gut instinct, but wasn't educated enough ... till now. Thanks guys. Will do some editing, looks like. $\endgroup$ Commented Nov 16, 2016 at 20:11

I would consider the idea it is a single tree that spans the entire planet, akin to a Banyan. To me this solves many problems, and potential adds interest.

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    $\begingroup$ Welcome to Worldbuilding, @luckyape. This answer is very short and is more suited to be a comment on the original question. $\endgroup$
    – kingledion
    Commented Nov 15, 2016 at 20:57
  • $\begingroup$ Thanks – agreed, I didn't have that priv at the time. $\endgroup$
    – luckyape
    Commented Nov 16, 2016 at 18:26
  • $\begingroup$ Luckyape, thankyou for your response. Yes, the Banyon tree, was my inspiration for this enviroment. Cypress trees as well, though both would not be feasible, in this particular planet. $\endgroup$ Commented Nov 16, 2016 at 20:15

A friend and I kinda worked through this once. You have floating plants and kelp forming clumps, basically the plants are a series of gas-bags with leaves and root. there are already floating plants but for the ocean you will need greater buoyancy hence the gasbags. picture the sargasso sea on steroids.

other types of plants colonize these mats adding larger plants, more gas bags, deeper roots. the roots start to collect debris and will house lots of animals, the roots of some plants may even be designed to tangle and hold animals for supplemental nutrients.you might have filter feeding animals also colonizign them and each dead plant is going to add more "soil" to the islands. eventually as the mats get large enough they begin to support mangrove like trees with light balsa like wood and maybe their own wood floats or coconut like growths.there trees would favor being wide and spread out instead of tall for stability. the more animals and plants colonize the mats the more debris is added when they die encouraging bigger plants. insects, crabs, maybe amphibians, and millions of fish would colonize such things.

the plants are held together by intertwining rooks and tendrils, and "islands" may be torn apart during storms if they get too big, and would occasionally sink. they would naturally be pushed towards the ocean gyri so soon you would have many "islands" close together or even joining.

on a water world these might very well have evolved from sargassum kelp. Humans would need to build platforms to live on, but would have to be careful cover too much and too many plants might die causing the whole thing to sink.

trees might drop floating twisty nuts that get tangled in in mats where they sprout after several years, giving the mats time to build up around them. the trees roots would spread wide to help hold the mat together and to get their nuts to the edge where they need to be.

  • $\begingroup$ John, thank you for your answer, and yes, the seaweed, seemed to be the closest example of Bladetree, except for root system, and size. (see new edit) $\endgroup$ Commented Nov 16, 2016 at 20:23

This idea will only work so far. Since the world is without land, there are no land masses to interrupt the development of storms, and they have an essentially unlimited length of wave development (called fetch). As a result, storm-driven waves will become enormous. When these waves encounter your "trees", unless the organism can flex freely it will break. This is similar to the maximum (about 300 feet or so) length of wooden ships. Beyond that length, wooden ships tend to break. And, since seasoned wood is stronger than green wood, you should assume that your "trees" are weaker than a wooden ship would be.

So in order to survive, the "trees" must consist of smallish solid parts interconnected by very strong, flexible tendrils, and there must be some built-in mechanism to prevent the solid parts from fusing.

  • $\begingroup$ To clarify:. The " masses" would be the flexing trees as big as continents, so yes they would interupt storms systems.. So what else? $\endgroup$ Commented Nov 15, 2016 at 19:14
  • $\begingroup$ @ConradR.SnyderII - Continent-sized "trees" will destroy the ocean by blocking the sunlight. The interior portions of these organisms will be unable to gain nutrients by predation, since the seas under them will be barren. $\endgroup$ Commented Nov 15, 2016 at 19:17
  • $\begingroup$ The underneath would not be barren, though. The hanging roots would provide shelter, and foundation. Upside down world, depending on minerals from vulcanized, Oceans floor. Not sunlight driven then, but chemically driven from minerals. yeah! $\endgroup$ Commented Nov 15, 2016 at 19:27
  • $\begingroup$ Yes this was my thinking, also, but, horizontally. Much like a two dementional diagram of a Family Tree. This way there would be more shores surface areas. Like a continuous folding labyrinth, not a maze, but linear, like labyrinth. Thanks, very inspiring, answer. $\endgroup$ Commented Nov 15, 2016 at 19:56
  • $\begingroup$ If the root system is extensive enough, it might be enough to prevent most damage from waves. $\endgroup$
    – Phil M
    Commented Nov 15, 2016 at 21:35

This is just conjecture...

It would seem that this concept would emphasis a simple ecosystem. I could see some symbiotic plants growing into the bark, and even pockets of dirt/dust (if nothing else than from decay). Highly probable that there would be diverse fungi, even to the point of having colorful seasonal "wildflower" species. The wind would be especially useful in spreading the spores so that the fungi can repopulate in "new" areas.

Vast insect swarms would travel in migration patterns following the supply of food. The more destructive swarms would nearly strip everything except the great tree. Other insects would be used for pollination and transferring seeds of plants that are unable to benefit from the wind.

Many of the larger and more intelligent animals in the branches would be of a flying/gliding type. It could be a feasible environment for creatures that look like fairies. There would also be grasping animals such as snakes, who are especially dangerous as they blend in with the branches. Finally there would also be primarily water dwellers who live entirely in or near the water.

Any human-like life would be warriors/hunters/gatherers as the environment does not allow farming, mining, etc.

  • $\begingroup$ Phil M. thank you for your "conjecture". Yes, the size, and enviroment, would support, many forms of life, above and below, see new edit. $\endgroup$ Commented Nov 16, 2016 at 20:19

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