Animals and people can migrate whether you like it or not; now the entire forest of trees gain mobility; in fact they can crawl, swim, leap and even fly.

What kind of wings can grow in a tree and allow itself to fly across a vast ocean? It may carry some soils and may even have leaves that look like cactus to store water, perhaps it will shed most of its leaves to reduce moisture lost but that would mean that the leaves cannot act like feathers. Upon reaching its destination it will burrow roots deep into the ground.

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    $\begingroup$ In an odd way, trees do that now. They take advantage of birds. By producing fruit that birds eat, the birds crap out the seeds in another location, with a nice "soil" included. $\endgroup$ – user11599 Sep 12 '15 at 4:24
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    $\begingroup$ I have one question. How exactly is the tree going to burrow it's root into the ground? As in, how is it going to dig? $\endgroup$ – Youstay Igo Sep 12 '15 at 6:27
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    $\begingroup$ @user11599: also, seeds that are blown by the wind are another example of this. $\endgroup$ – zeta Sep 12 '15 at 6:35
  • $\begingroup$ @Youstay Igo: like cordyceps the plant mind control a clan of moles, these half dead moles will dug sizable trench for the root while the carcasses decompose to provide nutrients :) $\endgroup$ – user6760 Sep 12 '15 at 7:01
  • $\begingroup$ Sounds like we aren't dealing with trees (plants) here but in fact an animal which happens to have photosynthesis capabilities. Am I right? $\endgroup$ – Youstay Igo Sep 12 '15 at 9:00

Ok, so you want to get trees that fly.

Let's see what you need for that:


OK, the first thing you need for flying trees is a way to generate uplift.

Why would the trees evolve uplift?

Certainly not in order to fly: With only little uplift, you cannot fly, but you first need to generate a little uplift in order to then evolve to uplift strong enough to fly.

So what would trees need that uplift for? Well, uplift basically means pushing air down. Now when stationary, pushing air down means that fresh air from above replaces it. So maybe the trees evolved in a low-CO2 environment, and the consumption of CO2 by the trees mean that the concentration of it went down. Therefore it was an advantage for the trees to ventilate fresh air with more CO2 into the forest.

How would the trees evolve uplift?

I think the most logical step would be to grow moveable branches that can act similar to wings, with leaves evolved to have a similar behaviour to the feathers of a bird's wing. The hard part would be to explain why they evolve the movable joints, as trees don't normally have that. But maybe there are many relatively fast moving, dense clouds, and being able to quickly move branches vastly improves the amount of light the tree can harvest.

Ability to remove the roots from the ground

Frankly, I have no idea why or how this would evolve. But since you are talking about crawling trees, I'll just assume that at the time when trees evolved flight, this had already evolved.

Ability to leave the ground

Bow that the basic properties are evolved, the next step is why trees would actually evolve to leave the ground. The how is easy: The uplift just gets strong enough to lift the tree when not rooted. The why could be that it is an advantage for the tree to shortly hover when animals start to eat from its bark. Since the animals which do that usually can't fly, by hovering the tree could get away from that animal.

Ability to full-fledged flight

Well, from that point on it is a quite direct path to full-fledged flight. Obviously it's an advantage to be able to hover for a longer time; also a better control of the hovering is advantageous. And with that comes the ability to actually change position; the advantage of that ability should be obvious.

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    $\begingroup$ You are missing the main point. The brain, the decision making and the CNS. You first need to describe how and why trees would evolve brains and decision making, before you get into things as uplift and root pull and stuff like that. $\endgroup$ – Youstay Igo Sep 12 '15 at 11:38
  • $\begingroup$ @YoustayIgo: Do you have any indication that you need to have a brain in order to fly? And why would the trees need decision making beyond the abilities plants already have? $\endgroup$ – celtschk Sep 12 '15 at 11:44
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    $\begingroup$ My question to O.P. => I have one question. How exactly is the tree going to burrow it's root into the ground? As in, how is it going to dig? – Youstay Igo. O.P.'s reply => @Youstay Igo: like cordyceps the plant mind control a clan of moles, these half dead moles will dug sizable trench for the root while the carcasses decompose to provide nutrients :) – user6760 $\endgroup$ – Youstay Igo Sep 12 '15 at 11:48
  • $\begingroup$ @YoustayIgo: I'm pretty sure cordyceps doesn't have a brain/CNS. $\endgroup$ – celtschk Sep 12 '15 at 11:53

Trees are quite passive in our world. I am not sure it will still look like trees with active wings.

Let's make them plane.

How could a tree plane ?

Longs boughs with large leaves. Some plants of our world are moving (carnivor plants, mimosa pudica...), your trees could have a slight ability to move leaves and boughs. Like sunflowers, they could turn in front of the sun and grow leaves which form will give the tree a global direction to move. Or it could move withe the wind (a seasonal wind blowing in the same direction several weeks/months for example)

In order to stay in the air, it could use the sun to heat the air under big balloons-like leaves. Trees would look more like a shoal of jellyfish than trees, though.

You could imagine a symbiosis with a micro organism rejecting a light gas that the tree could use to swell its leaves.

How could the tree survive in the air ?

The major issue is that the tree needs nutrients. I think it can find some water in the air. If it uses the sun or another way to warm air up to float in the air, there should be mistiness.

Either the tree floats very low and collects some nutrients from roots lying on the ground (or plankton on the top of the see ?), either the flying part of its life is like winter sleep : the tree is just floating around with minimal activity and does not reproduce, grows flowers nor fruits. It could be an early stage of development of the tree, from a little floating seed to a bunch of balloons-leaves until it reaches the ground and start growing properly (but I feel like a seed needs more nutrients than what the air can give)

Where did evolution find such an idea ?

In a bad ground trees could not survive for long, so they began to move a little, with their roots growing on a side while roots on the other side where dying, making the whole tree move.

Then, nature found that it was far more easy to make a tree move if it was lighter, and leaves began to carry a part of the weight and the trunk became lighter.

Then, flying trees began to slowly walk and float while roots became thiner to absorb nutrients then die and grow elsewhere. Either they are still doing this, either they began to grow big trunks only when finding a good place.

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  • $\begingroup$ I'm not an english native speaker, and i'm not sure about a few words. $\endgroup$ – Tyrabel Sep 12 '15 at 13:04

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